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 A109582 #7 Aug 19 2022 14:38:54 %S A109582 -1,1,-2,0,24,-240,1440,-5040,-40320,1088640,-14515200,119750400,0, %T A109582 -24908083200,610248038400,-9153720576000,62768369664000, %U A109582 1422749712384000,-70426110763008000,1703031405723648000,-24329020081766400000,-51090942171709440000 %N A109582 Expansion of e.g.f.: -1/(1+x-x^3). %F A109582 E.g.f.: -1/(1+x-x^3). %F A109582 a(n) = n!*A104769(n+1). - _R. J. Mathar_, Aug 20 2021 %F A109582 D-finite with recurrence a(n) +n*a(n-1) -n*(n-1)*(n-2)*a(n-3) = 0. - _R. J. Mathar_, Aug 20 2021 %p A109582 g:=-1/(1+x-x^3):gser:=series(g,x=0,26): -1,seq(n!*coeff(gser,x^n),n=1..22); %Y A109582 Cf. A050935, A104769. %K A109582 sign %O A109582 0,3 %A A109582 _Roger L. Bagula_, Jun 29 2005