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A321418 Number of n element multisets of the 15th roots of unity with zero sum. 3
1, 0, 0, 5, 0, 3, 15, 0, 15, 35, 6, 45, 70, 30, 105, 135, 90, 210, 255, 210, 390, 465, 420, 690, 810, 771, 1170, 1345, 1335, 1905, 2153, 2205, 2985, 3345, 3495, 4536, 5060, 5340, 6720, 7465, 7920, 9735, 10755, 11460, 13815, 15180, 16230, 19230, 21045, 22545 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Equivalently, the number of closed convex paths of length n whose steps are the 15th roots of unity up to translation.

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..1000

FORMULA

G.f.: (1 - x^15)/((1 - x^3)^5 * (1 - x^5)^3).

PROG

(PARI) Vec((1 - x^15)/((1 - x^3)^5 * (1 - x^5)^3) + O(x^50))

CROSSREFS

Cf. A198805, A321419.

Sequence in context: A182567 A339457 A300728 * A225424 A202626 A011995

Adjacent sequences:  A321415 A321416 A321417 * A321419 A321420 A321421

KEYWORD

nonn,easy

AUTHOR

Andrew Howroyd, Nov 09 2018

STATUS

approved

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Last modified March 6 04:38 EST 2021. Contains 341841 sequences. (Running on oeis4.)