A321418 Number of n element multisets of the 15th roots of unity with zero sum.

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

Offset: 0

Author

Andrew Howroyd, Nov 09 2018

Keywords

• nonn
• easy

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

Crossrefs

Cf. A198805, A321419.

Programs

PARI

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

Formula

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