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 A176408 #12 Jun 02 2025 02:52:02 %S A176408 1,0,3,12,75,522,4179,37608,376083,4136910,49642923,645357996, %T A176408 9035011947,135525179202,2168402867235,36862848742992,663531277373859, %U A176408 12607094270103318 %N A176408 a(n) = (n+1)*(a(n-1) +a(n-2)) n>1, a(0)=1,a(1)=0. %C A176408 a(n) is one of two "basis" sequences for sequences of the form s(0)=a,s(1)=b,s(n)=(n+1)(s(n-1)+s(n-2)), n>1, the other being A006347. %C A176408 s(n) = a*a(n) + b* A006347(n+1). %C A176408 s(n) = 1/2*(b-2*a)(n+2)! +(3*a-b)*floor(((n+2)!+1)/e). %H A176408 Indranil Ghosh, <a href="/A176408/b176408.txt">Table of n, a(n) for n = 0..447</a> %H A176408 Michael Wallner, <a href="https://arxiv.org/abs/1706.07163">A bijection of plane increasing trees with relaxed binary trees of right height at most one</a>, arXiv:1706.07163 [math.CO], 2017, Table 2 on p. 13. %F A176408 a(n) = 3*floor(((n+2)!+1)/e) - (n+2)!. %F A176408 a(n) = 3* A000166(n+1) - (n+2)!, where A000166 are the subfactorial numbers. %e A176408 a(2)= 3*9-24=3, a(3)= 3*44-120=12, a(4)= 3*265-720=75, ... %p A176408 seq(3*floor(((n+2)!+1)/E) - (n+2)!,n=1..20); %Y A176408 Cf. A000166, A006347. %K A176408 nonn %O A176408 0,3 %A A176408 _Gary Detlefs_, Apr 16 2010 %E A176408 Data section corrected by _Indranil Ghosh_, Feb 15 2017