A198805 Number of closed paths of length n whose steps are 15th roots of unity, U_15(n).

1, 0, 0, 30, 0, 360, 7650, 0, 302400, 4544400, 11226600, 324324000, 4310633250, 24324300000, 437404968000, 5634178329780, 45972927000000, 697866761592000, 8962716395833200, 88725951057744000, 1258898645656852200

Offset

0,4

Comments

U_15(n), (comment in article): For each m >= 1, the sequence (U_m(N)), N >= 0 is P-recursive but is not algebraic when m > 2.

Links

Table of n, a(n) for n=0..20.

Gilbert Labelle and Annie Lacasse, Closed paths whose steps are roots of unity, in FPSAC 2011, Reykjavik, Iceland DMTCS proc. AO, 2011, 599-610.

Crossrefs

Cf. A198808, A321418.

Sequence in context: A022068 A277043 A361058 * A030128 A137348 A137737

Adjacent sequences: A198802 A198803 A198804 * A198806 A198807 A198808

Keyword

nonn

Author

Simon Plouffe, Oct 30 2011

Status

approved