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 A337059 #10 Aug 29 2020 02:13:31 %S A337059 1,1,3,12,67,461,3823,36933,407963,5068909,69982083,1062784273, %T A337059 17607354955,316012688213,6108011298847,126490611884013, %U A337059 2794122884322635,65578524701197341,1629676370022564219,42748628870263418761,1180373377691425730235 %N A337059 E.g.f.: 1 / (2 + x^3/6 - exp(x)). %H A337059 Robert Israel, <a href="/A337059/b337059.txt">Table of n, a(n) for n = 0..426</a> %F A337059 a(0) = a(1) = 1; a(n) = n * (a(n-1) + (n-1) * a(n-2) / 2) + Sum_{k=4..n} binomial(n,k) * a(n-k). %p A337059 S:= series(1/(2+x^3/6-exp(x)),x,31): %p A337059 seq(coeff(S,x,i)*i!,i=0..30); # _Robert Israel_, Aug 28 2020 %t A337059 nmax = 20; CoefficientList[Series[1/(2 + x^3/6 - Exp[x]), {x, 0, nmax}], x] Range[0, nmax]! %t A337059 a[0] = a[1] = 1; a[n_] := a[n] = n (a[n - 1] + (n - 1) a[n - 2]/2) + Sum[Binomial[n, k] a[n - k], {k, 4, n}]; Table[a[n], {n, 0, 20}] %Y A337059 Cf. A000670, A032032, A124504, A232475, A337058. %K A337059 nonn %O A337059 0,3 %A A337059 _Ilya Gutkovskiy_, Aug 13 2020