OFFSET
0,7
FORMULA
a(n) = 2*(n-1) * a(n-1) - (n-1)*(n-2) * a(n-2) + binomial(n-1,4) * a(n-5) - 4*binomial(n-1,5) * a(n-6) for n > 5.
From Seiichi Manyama, Jun 17 2024: (Start)
a(n) = n! * Sum_{k=0..floor(n/5)} binomial(n-4*k-1,n-5*k)/(120^k * k!).
a(0) = 1; a(n) = ((n-1)!/120) * Sum_{k=5..n} k * a(n-k)/(n-k)!. (End)
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x^5/(120*(1-x)))))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 15 2023
STATUS
approved