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 A066224 #27 Jul 02 2025 16:02:01
%S A066224 1,4,26,232,2620,35696,568504,10349536,211799312,4809701440,
%T A066224 119952692896,3257843882624,95680443760576,3020676745975552,
%U A066224 101990226254706560,3666624057550245376,139813029266338603264
%N A066224 Bisection of A000085.
%F A066224 a(n) = n!*2^n*LaguerreL(n, 1/2, -1/2). - _Vladeta Jovovic_, May 10 2003
%F A066224 a(n) = sum(n!*(2^(n-m))*binomial(n+1/2,n-m)/m!,m=0..n), n>=0.
%F A066224 a(n) ~ n^(n+1/2)*2^n*exp(-n+sqrt(2*n)-1/4) * (1 + 19/(24*sqrt(2*n))). - _Vaclav Kotesovec_, Jun 22 2013
%F A066224 a(n+2) - 4*(n+2)*a(n+1) + 2*(n+1)*(2*n+3)*a(n) = 0 - _Emanuele Munarini_, Aug 31 2017
%p A066224 a := proc(n) option remember: if n = 0 then RETURN(1) fi: if n = 1 then RETURN(1) fi: a(n-1)+(n-1)*a(n-2): end: for i from 1 to 61 by 2 do printf(`%d,`,a(i)) od: # _James Sellers_, Feb 11 2002
%t A066224 Table[n! 2^n LaguerreL[n,1/2,-1/2],{n,0,20}] (* _Harvey P. Dale_, Mar 11 2013 *)
%t A066224 Table[(-2)^n HypergeometricU[-n, 3/2, -(1/2)], {n, 0, 90}] (* _Emanuele Munarini_, Aug 31 2017 *)
%Y A066224 Cf. A066223.
%Y A066224 Unsigned row sums of A130757.
%K A066224 nonn,easy
%O A066224 0,2
%A A066224 _N. J. A. Sloane_, Dec 19 2001
%E A066224 More terms from _James Sellers_, Feb 11 2002