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 A306534 #7 Feb 22 2019 05:17:17 %S A306534 0,0,2,0,1,6,0,1,3,12,0,1,2,4,20,0,1,2,4,7,30,0,1,2,3,5,8,42,0,1,2,3, %T A306534 5,6,10,56,0,1,2,3,4,6,8,11,72,0,1,2,3,4,6,7,9,15,90,0,1,2,3,4,5,7,8, %U A306534 10,16,110,0,1,2,3,4,5,7,8,10,13,18,132,0,1,2,3,4,5,6,8,9,11,14,19,156 %N A306534 Square array A(n,k), n >= 0, k >= 1, read by antidiagonals: A(n,k) = Sum_{j=0..n} floor(n/k^j). %F A306534 G.f. of column k (for k > 1): (1/(1 - x)) * Sum_{j>=0} x^(k^j)/(1 - x^(k^j)). %e A306534 Square array begins: %e A306534 0, 0, 0, 0, 0, 0, ... %e A306534 2, 1, 1, 1, 1, 1, ... %e A306534 6, 3, 2, 2, 2, 2, ... %e A306534 12, 4, 4, 3, 3, 3, ... %e A306534 20, 7, 5, 5, 4, 4, ... %e A306534 30, 8, 6, 6, 6, 5, ... %t A306534 Table[Function[k, Sum[Floor[n/k^j], {j, 0, n}]][i - n + 1], {i, 0, 12}, {n, 0, i}] // Flatten %Y A306534 Columns k=1..4 give A002378, A005187, A004128, A087069. %Y A306534 Cf. A306533. %K A306534 nonn,tabl %O A306534 0,3 %A A306534 _Ilya Gutkovskiy_, Feb 22 2019