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 A108189 #11 Jun 02 2025 00:28:00
%S A108189 0,1,1,3,8,20,66,196,688,2358,8840,33506,134376,550498,2350348,
%T A108189 10273110,46413536,214598786,1020359628,4959234118,24699168280,
%U A108189 125571468666,652484852756,3456224649758,18673351714128,102717737562850
%N A108189 a(n) = (n-1)*(a(n-2)+a(n-3)).
%C A108189 Recurrence is similar to A000166 or A000931.
%H A108189 Robert Israel, <a href="/A108189/b108189.txt">Table of n, a(n) for n = 1..800</a>
%F A108189 a(n) ~ (3/4)*sqrt(2) * exp(sqrt(n)-n/2-1/4)*n^(n/2-1/2) * (1-53/(24*sqrt(n))). - _Vaclav Kotesovec_, Dec 28 2012
%p A108189 f:= gfun:-rectoproc({a(n) = (n-1)*(a(n-2)+a(n-3)),a(1)=0,a(2)=1,a(3)=1},a(n),remember):
%p A108189 map(f, [$1..40]); # _Robert Israel_, Feb 20 2017
%t A108189 F[1] = 0; F[2] = 1; F[3] = 1; F[n__] := F[n] = (n - 1)*( F[n - 2] + F[n - 3]) a = Table[F[n], {n, 1, 25}]
%Y A108189 Cf. A000166, A000213, A000931.
%K A108189 nonn
%O A108189 1,4
%A A108189 _Roger L. Bagula_, Jun 14 2005