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 A383023 #14 Apr 13 2025 08:19:10 %S A383023 1,2,1,3,3,0,4,6,2,1,5,10,8,6,0,6,15,20,24,6,0,7,21,40,70,48,11,0,8, %T A383023 28,70,165,204,124,18,1,9,36,112,336,624,690,312,36,0,10,45,168,616, %U A383023 1554,2620,2340,834,56,0,11,55,240,1044,3360,7805,11160,8230,2184,105,0 %N A383023 Square array A(n,k), n >= 1, k >= 1, read by antidiagonals downwards, where A(n,k) is the n-th term of the inverse Weigh transform of j-> k^j. %H A383023 Christian G. Bower, <a href="https://oeis.org/transforms_pari.txt">PARI programs for transforms</a>, 2007. %H A383023 N. J. A. Sloane, <a href="/transforms.txt">Maple programs for transforms</a>, 2001-2020. %F A383023 A(n,k) = (1/n) * (k^n + Sum_{d<n and d|n} (-1)^(n/d) * d * A(d,k)). %F A383023 Product_{n>=1} (1 + x^n)^A(n,k) = 1/(1 - k*x). %e A383023 Square array begins: %e A383023 1, 2, 3, 4, 5, 6, 7, ... %e A383023 1, 3, 6, 10, 15, 21, 28, ... %e A383023 0, 2, 8, 20, 40, 70, 112, ... %e A383023 1, 6, 24, 70, 165, 336, 616, ... %e A383023 0, 6, 48, 204, 624, 1554, 3360, ... %e A383023 0, 11, 124, 690, 2620, 7805, 19656, ... %e A383023 0, 18, 312, 2340, 11160, 39990, 117648, ... %Y A383023 Columns k=1..5 give A209229, A306156, A306157, A306158, A306159. %Y A383023 Cf. A074650. %K A383023 nonn,tabl %O A383023 1,2 %A A383023 _Seiichi Manyama_, Apr 12 2025