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 A384777 #27 Jun 10 2025 13:57:14 %S A384777 1,1,0,1,1,0,1,2,3,0,1,3,7,19,0,1,4,12,44,221,0,1,5,18,76,489,4597,0, %T A384777 1,6,25,116,813,9750,174007,0,1,7,33,165,1203,15543,358895,12328367,0, %U A384777 1,8,42,224,1670,22072,555696,25040728,1674839513,0,1,9,52,294,2226,29446,765572,38156448,3375603329,443624694633,0 %N A384777 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where column k is the expansion of B(x)^k, where B(x) is the g.f. of A382450. %F A384777 A(n,0) = 0^n; A(n,k) = k * Sum_{j=0..n} 2^(n-j) * binomial(n+k,j)/(n+k) * A(n-j,j). %e A384777 Square array begins: %e A384777 1, 1, 1, 1, 1, 1, ... %e A384777 0, 1, 2, 3, 4, 5, ... %e A384777 0, 3, 7, 12, 18, 25, ... %e A384777 0, 19, 44, 76, 116, 165, ... %e A384777 0, 221, 489, 813, 1203, 1670, ... %e A384777 0, 4597, 9750, 15543, 22072, 29446, ... %o A384777 (PARI) a(n, k) = if(k==0, 0^n, k*sum(j=0, n, 2^(n-j)*binomial(n+k,j)/(n+k)*a(n-j, j))); %Y A384777 Columns k=0..1 give A000007, A382450. %Y A384777 Cf. A379598. %K A384777 nonn,tabl %O A384777 0,8 %A A384777 _Seiichi Manyama_, Jun 10 2025