cp's OEIS Frontend

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.

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.

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%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