OFFSET
0,2
FORMULA
a(0) = 1; a(n) = -3 * (n-1)! * Sum_{k=1..min(3,n)} binomial(2,k-1) * a(n-k)/(n-k)!.
a(n) = Sum_{k=0..n} 3^k * Stirling1(n,k) * A000587(k).
D-finite with recurrence a(n) +3*a(n-1) +6*(n-1)*a(n-2) +3*(n-1)*(n-2)*a(n-3)=0. - R. J. Mathar, Feb 02 2024
MAPLE
A369751 := proc(n)
option remember ;
if n =0 then
1;
else
add( binomial(2, k-1) * procname(n-k)/(n-k)!, k=1..min(3, n)) ;
-3*(n-1)!*% ;
end if;
end proc:
seq(A369751(n), n=0..20) ; # R. J. Mathar, Feb 02 2024
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(1-(1+x)^3)))
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Jan 30 2024
STATUS
approved