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 A274276 #11 Jun 23 2016 02:06:51
%S A274276 1,1,2,10,80,776,8992,130768,2252672,43823872,957193856,23369928704,
%T A274276 629680631296,18514472015872,590350181439488,20311856724176896,
%U A274276 749913022501879808,29561045244530032640,1239353203580700000256,55077035791625925492736,2586090541400666789543936,127922890235433583945056256,6649362432158408977810522112,362360171399316029979428126720,20658795751396952768159379619840
%N A274276 E.g.f. A(x) satisfies: A( sqrt( A(x^2*exp(-2*x)) ) ) = x, where A(x) = Sum_{n>=1} a(n)*x^n/(n-1)!.
%H A274276 Paul D. Hanna and Vaclav Kotesovec, <a href="/A274276/b274276.txt">Table of n, a(n) for n = 1..200</a> (first 150 terms from Paul D. Hanna)
%F A274276 a(n) = A274275(n)/n.
%F A274276 E.g.f. A(x) = Sum_{n>=1} a(n) * x^n / (n-1)! satisfies:
%F A274276 (1) A( sqrt( A(x^2*exp(2*x)) ) ) = -LambertW(-x*exp(x)).
%F A274276 (2) A(x) = Series_Reversion( sqrt( A(x^2*exp(-x)) ) ).
%F A274276 (3) A( A(x)^2 * exp(-2*A(x)) ) = x^2.
%F A274276 (4) A(-A(x)^2 * exp(-2*A(x)) ) = -LambertW(x^2*exp(-x^2)).
%F A274276 a(n)/n! ~ c * d^n / n^(5/2), where d = 2.52462188117..., c = 0.36965356... . - _Vaclav Kotesovec_, Jun 23 2016
%e A274276 E.g.f.: A(x) = x + x^2 + 2*x^3/2! + 10*x^4/3! + 80*x^5/4! + 776*x^6/5! + 8992*x^7/6! + 130768*x^8/7! + 2252672*x^9/8! + 43823872*x^10/9! + 957193856*x^11/10! +...
%e A274276 such that A( sqrt( A(x^2*exp(-2*x)) ) ) = x.
%o A274276 (PARI) {a(n) = my(A=x); for(i=1, n, A = serreverse( sqrt( subst(A, x, x^2*exp(-2*x +x*O(x^n))) ) ) ); (n-1)!*polcoeff(A,n)}
%o A274276 for(n=1,30,print1(a(n),", "))
%Y A274276 Cf. A274275.
%K A274276 nonn
%O A274276 1,3
%A A274276 _Paul D. Hanna_, Jun 17 2016