OFFSET
0,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Jia Huang and Erkko Lehtonen, Associative-commutative spectra for some varieties of groupoids, arXiv:2401.15786 [math.CO], 2024. See p. 10.
FORMULA
a(n) = e*Gamma(n+3,1)-(3/2)*(n+2)!, where Gamma(a,x) is the incomplete gamma function. [Bruno Berselli, Dec 24 2012]
a(n) = (n+3)*a(n-1) - (n+1)*a(n-2). - Vaclav Kotesovec, Aug 13 2013
a(n) ~ (exp(1)-3/2)*sqrt(2*Pi)*exp(-n)*n^(n+5/2). - Vaclav Kotesovec, Aug 13 2013
MATHEMATICA
RecurrenceTable[{a[0]==2, a[n]==(n+2)*a[n-1] + 1}, a, {n, 20}] (* Vincenzo Librandi, Dec 23 2012 *)
PROG
(Magma) [n le 1 select 2 else (n+1)*Self(n-1)+1: n in [1..20]]; // Vincenzo Librandi, Dec 22 2012
CROSSREFS
KEYWORD
nonn
AUTHOR
Olivier Gérard, Nov 02 2012
EXTENSIONS
Edited by Vincenzo Librandi and N. J. A. Sloane, Dec 24 2012
STATUS
approved