SanD primes and numbers

Freeman J. Dyson, Norman E. Frankel, Anthony J. Guttmann

We define S(um)anD(ifference) numbers as ordered pairs $(m,m+\Delta )$ such that the digital-sum $DS(m(m+\Delta ))=\Delta .$ We consider both the decimal and the binary case. If both $m$ and $m+Δ…