18 papers
Non-adjacent triples of cells in a triangular grid: proofs of three conjectured generating functions
Tong Niu
Let $\Tn$ be the triangular grid of side , with its unit cells, and let two cells be side-adjacent if they share an edge and point-adjacent if they share a vertex. We coun…
The first descent in a standard Young tableau of shape
Tong Niu
Let be the number of standard Young tableaux of shape whose entry in row , column is odd; equivalently, the number of those whose first descent is even. Thi…
Toward a Formally Verified Optimality Certificate for OGR(29): A SAT-Encoding Methods Note with Small-Case Demos
Tong Niu
A Golomb ruler of order~ is an integer set whose pairwise differences () are all distinct. The optimal Golomb ruler pr…
An exact small- computation of the minimum 2-coloring discrepancy of
Tong Niu
For an integer and an order , write for the minimum, over all -colourings , of $\max_{\mathcal{S}} \mathrm{…
Parity vectors and paradoxical sequences in the accelerated Collatz map
Tong Niu
This note studies parity vectors and paradoxical sequences in the accelerated Collatz iteration for odd, for even. Building on Rozier and Ter…
The pebbling number of Fibonacci cubes
Tong Niu
The -th Fibonacci cube is the subgraph of the hypercube induced by binary strings with no two consecutive ones. We determine for , so the peb…
An explicit algebraic generating function for OEIS A348410
Tong Niu
For the OEIS sequence A348410, P. Bala recorded in February 2022 two equivalent closed forms, and a single-index binomial sum. R. J. Mathar (Oc…
Three short proofs of Mathar's 2014 conjecture for OEIS A002627
Tong Niu
For the OEIS sequence A002627, defined by the inhomogeneous first-order recurrence with , R.~J.~Mathar recorded in February 2014 the conjectured se…
A short proof of Mathar's 2013 recurrence conjecture for the reversible-binary-string sequence A032123
Tong Niu
For the OEIS sequence A032123, the number of length- black-and-white strings with black beads, considered up to reversal, R. J. Mathar contributed in November 2013 the conj…
Improved Upper Bounds on the Pebbling Numbers of the Blanuša Snarks
Tong Niu
The two Blanuša snarks and are 3-regular graphs on 18 vertices. Dantas, Lordelo, Niedermaier and Nogueira (Discrete Appl. Math. 361, 2025, pp. 336-346) established the…
Graceful labelings of spiders with three-edge legs and pendant leaves at the center
Tong Niu
A graph on edges is graceful if there is an injection whose induced edge labels are exactly $\{1, 2, \l…
Size-4 Counterexamples to the Sidon-Extension Conjecture
Tong Niu
A finite set is a Sidon set if its pairwise differences are distinct. Recall that a perfect difference set (PDS) of order is a set $B \subset \mathbb{Z}_…
A short proof of Mathar's 2021 recurrence conjecture for the Lehmer-Comtet diagonal A045406
Tong Niu
For OEIS sequence A045406, the column-2 diagonal of the Lehmer-Comtet triangle A008296, R. J. Mathar contributed in September 2021 the conjectured order-2 P-recursive recurrence \[…
A short proof of Mathar's 2020 recurrence conjecture for the generalized-Stirling sequence A001711
Tong Niu
For the OEIS sequence A001711, contributed by N. J. A. Sloane long before the on-line era and identified there as the diagonal of a generalized-Stirling triangle, R. J.…
The vertex Folkman number equals~
Tong Niu
The vertex Folkman number is the smallest for which there exists a -free graph on vertices whose vertices cannot be -colored without producing a monoch…
A short proof of Mathar's 2013 recurrence conjecture for the Laguerre sequence~A025166
Tong Niu
For the OEIS sequence A025166, defined by where is the Laguerre polynomial of degree , R.~J.~Mathar contributed in February 2013 the conj…
A short proof of Mathar's 2016 recurrence conjecture for OEIS A176677
Tong Niu
For the OEIS sequence A176677, defined by the quadratic convolution recurrence and for , R.~J.~Mathar contributed…
A short proof of Mathar's 2013 recurrence conjecture for the Meixner sequence A214615
Tong Niu
For the OEIS sequence A214615, defined by where is the -th Meixner polynomial satisfying , R.~J.~Mathar c…