This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A362367 #9 Apr 20 2023 14:44:11 %S A362367 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3,2,2,2,2,2,2,2,2,2, %T A362367 2,2,2,2,2,2,2,2,2,2,2,2,2,2,3,2,2,3,2,2,2,2,2,2,3,2,4,2,3,2,2,2,2,2, %U A362367 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,5,5,5,2,2,2,2,2 %N A362367 Square array A(n, k), n, k >= 0, read by antidiagonals; A(n, k) is the least base >= 2 where the product n * k can be computed without carry. %H A362367 Rémy Sigrist, <a href="/A362367/b362367.txt">Table of n, a(n) for n = 0..10010</a> %H A362367 Rémy Sigrist, <a href="/A362367/a362367.png">Colored representation of the array for n, k <= 1024</a> (the color is function of A(n, k), black pixels denote 2's) %F A362367 A(n, k) <= max(2, n*k + 1). %F A362367 A(n, k) = A(k, n). %F A362367 A(n, 0) = A(n, 1) = A(n, 2) = 2. %F A362367 A(n, n) = A319478(n). %e A362367 Array A(n, k) begins: %e A362367 n\k | 0 1 2 3 4 5 6 7 8 9 10 11 12 %e A362367 ----+----------------------------------------- %e A362367 0 | 2 2 2 2 2 2 2 2 2 2 2 2 2 %e A362367 1 | 2 2 2 2 2 2 2 2 2 2 2 2 2 %e A362367 2 | 2 2 2 2 2 2 2 2 2 2 2 2 2 %e A362367 3 | 2 2 2 3 2 2 3 3 2 2 2 3 3 %e A362367 4 | 2 2 2 2 2 2 2 2 2 2 2 2 2 %e A362367 5 | 2 2 2 2 2 4 2 5 2 2 3 5 2 %e A362367 6 | 2 2 2 3 2 2 5 5 2 2 2 5 3 %e A362367 7 | 2 2 2 3 2 5 5 5 2 2 3 7 6 %e A362367 8 | 2 2 2 2 2 2 2 2 2 2 2 2 2 %e A362367 9 | 2 2 2 2 2 2 2 2 2 3 2 3 2 %e A362367 10 | 2 2 2 2 2 3 2 3 2 2 3 5 2 %e A362367 11 | 2 2 2 3 2 5 5 7 2 3 5 5 3 %e A362367 12 | 2 2 2 3 2 2 3 6 2 2 2 3 3 %o A362367 (PARI) A(n, k) = { for (b = 2, oo, if (sumdigits(n*k, b) == sumdigits(n, b) * sumdigits(k, b), return (b););); } %Y A362367 Cf. A319478, A362366. %K A362367 nonn,base,tabl %O A362367 0,1 %A A362367 _Rémy Sigrist_, Apr 17 2023