A324965 Partial sums of A324964.

0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11

Offset

0,6

Comments

Conjecture: a(n) <= A324918(n) for all n >= 13.

Links

Table of n, a(n) for n=0..75.

C. Defant, Counting 3-stack-sortable permutations, arXiv:1903.09138 [math.CO], 2019.

Prog

(PARI) f(n) = binomial(3*n, n)*2/((n+1)*(2*n+1)) % 2; \\ A324964
a(n) = sum(k=0, n, f(k)); \\ Michel Marcus, Apr 02 2019

Crossrefs

Cf. A324964, A324965, A324918.

Sequence in context: A074280 A000523 A124156 * A072749 A066490 A156685

Adjacent sequences: A324962 A324963 A324964 * A324966 A324967 A324968

Keyword

nonn

Author

Colin Defant, Mar 21 2019

Status

approved