A063781 a(n) is the number of pairs of integer quadruples (b_1, b_2, b_3, b_4) and (c_1, c_2, c_3, c_4) satisfying 1 <= b_1 < b_2 < b_3 < b_4 < n, 1 <= c_1 < c_2 < c_3 < c_4 < n, b_i != c_j for all i,j = 1,2,3,4 and Product_{i=1..4} sin(2*Pi*b_i/n) = Product_{i=1..4} sin(2*Pi*c_i/n).

0, 1, 3, 4, 5, 9, 18, 17, 41, 29, 84, 45, 167, 66, 253, 93, 386, 126, 534, 166, 782, 214, 966, 270, 1380, 335, 1601, 410, 3053, 495, 2448, 591, 3135, 699, 3546, 819, 4785, 952, 4947, 1099, 8350, 1260, 6660, 1436, 8804, 1628, 8724, 1836, 10620, 2061, 11191

Offset

8,3

Links

Eckard Specht, Table of n, a(n) for n = 8..200

Example

For n=9, the only solution is (1, 4, 6, 7), (2, 3, 5, 8). - Sean A. Irvine, May 30 2023

Crossrefs

Cf. A063780.

Sequence in context: A195971 A080552 A215176 * A257041 A346603 A056797

Adjacent sequences: A063778 A063779 A063780 * A063782 A063783 A063784

Keyword

nonn

Author

Eckard Specht, Aug 17 2001

Extensions

Revised by Sean A. Irvine, May 30 2023

Status

approved