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A324965 Partial sums of A324964. 3
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified July 8 19:01 EDT 2020. Contains 335524 sequences. (Running on oeis4.)