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 A362572 #20 Aug 05 2025 07:47:34 %S A362572 1,1,1,4,13,76,421,3361,26209,267688,2689201,33579811,412800961, %T A362572 6103089994,88754687113,1517513934301,25487131948321,495009722435176, %U A362572 9430633148123809,205154208873930763,4371962638221712801,105330237499426955926 %N A362572 E.g.f. satisfies A(x) = exp(x * A(x)^(x/2)). %H A362572 Seiichi Manyama, <a href="/A362572/b362572.txt">Table of n, a(n) for n = 0..439</a> %H A362572 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LambertW-Function.html">Lambert W-Function</a>. %F A362572 E.g.f.: (-2 * LambertW(-x^2/2) / x^2)^(2/x) = exp(-2 * LambertW(-x^2/2) / x) = exp(x * exp(-LambertW(-x^2/2))). %F A362572 a(n) = n! * Sum_{k=0..floor(n/2)} ((n-k)/2)^k * binomial(n-k-1,k)/(n-k)!. %F A362572 E.g.f.: Sum_{k>=0} (k*x/2 + 1)^(k-1) * x^k / k!. %F A362572 a(n) ~ (exp(sqrt(2)*exp(1/2)) - (-1)^n*exp(-sqrt(2)*exp(1/2))) * n^(n-1) / (2^(n/2 - 1) * exp((n-1)/2)). - _Vaclav Kotesovec_, Aug 05 2025 %o A362572 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x*exp(-lambertw(-x^2/2))))) %Y A362572 Cf. A000272, A362573. %Y A362572 Cf. A361777. %K A362572 nonn %O A362572 0,4 %A A362572 _Seiichi Manyama_, Apr 25 2023