A344229 a(n) = n*a(n-1) + n^signum(n mod 4), a(0) = 1.

1, 2, 6, 21, 85, 430, 2586, 18109, 144873, 1303866, 13038670, 143425381, 1721104573, 22374359462, 313241032482, 4698615487245, 75177847795921, 1278023412530674, 23004421425552150, 437084007085490869, 8741680141709817381, 183575282975906165022

Offset: 0

Author

Alois P. Heinz, May 12 2021

Keywords

• nonn

Comments

This sequence is one of many possible solutions to puzzle 16 on the Meerdaelquiz puzzle page, cf. the Delestinne link and A090805.

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..450
• Hugo Delestinne, Meerdaelquiz [broken link]
• N. J. A. Sloane and Brady Haran, A Sequence with a Mistake, Numberphile video (2021)

Crossrefs

Cf. A000142, A000522, A010873, A033540, A053817, A057427, A090805, A166486, A277506.

Programs

Maple

a:= proc(n) a(n):= n*a(n-1) + n^signum(n mod 4) end: a(0):= 1:
seq(a(n), n=0..23);