OFFSET
0,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..449
FORMULA
a(n) = n * a(n-1) - a(n-4) + n * a(n-5) for n > 4.
a(n) ~ n! * (1 - 1/n^4 - 6/n^5 - 25/n^6 - 90/n^7 - 300/n^8 - 938/n^9 - 2563/n^10 - ...). - Vaclav Kotesovec, Nov 25 2022
PROG
(PARI) a(n) = sum(k=0, n\4, (-1)^k*(n-4*k)!);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 23 2022
STATUS
approved