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 A088501 #20 May 22 2022 09:50:04 %S A088501 1,2,6,28,172,1328,12272,132480,1633344,22663104,349324608,5923548288, %T A088501 109570736256,2195765044224,47386235513856,1095689316882432, %U A088501 27023900076988416,708173307424456704,19649589144733089792 %N A088501 Expansion of e.g.f. 1/(1-2*log(1+x)). %H A088501 Seiichi Manyama, <a href="/A088501/b088501.txt">Table of n, a(n) for n = 0..419</a> %F A088501 a(n) = Sum_{k=0..n} Stirling1(n, k)*k!*2^k. %F A088501 a(n) ~ n! * exp(1/2) / (2 * (exp(1/2)-1)^(n+1)). - _Vaclav Kotesovec_, May 03 2015 %F A088501 a(0) = 1; a(n) = 2 * Sum_{k=1..n} (-1)^(k-1) * (k-1)! * binomial(n,k) * a(n-k). - _Seiichi Manyama_, May 22 2022 %t A088501 CoefficientList[Series[1/(1-2*Log[1+x]), {x, 0, 20}], x] * Range[0, 20]! (* _Vaclav Kotesovec_, May 03 2015 *) %o A088501 (PARI) a(n) = sum(k=0, n, k!*2^k*stirling(n, k, 1)); \\ _Seiichi Manyama_, Feb 03 2022 %o A088501 (PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(1/(1-2*log(1+x)))) \\ _Seiichi Manyama_, Feb 03 2022 %o A088501 (PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=2*sum(j=1, i, (-1)^(j-1)*(j-1)!*binomial(i, j)*v[i-j+1])); v; \\ _Seiichi Manyama_, May 22 2022 %Y A088501 Column k=2 of A320080. %K A088501 easy,nonn %O A088501 0,2 %A A088501 _Vladeta Jovovic_, Nov 12 2003