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

0,2

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]

Neil Sloane and Brady Haran, A Sequence with a Mistake, Numberphile video (2021)

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);

Crossrefs

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

Sequence in context: A326276 A099947 A121726 * A090805 A150226 A326335

Adjacent sequences: A344226 A344227 A344228 * A344230 A344231 A344232

Keyword

nonn

Author

Alois P. Heinz, May 12 2021

Status

approved