A013914 Number of distinct nonzero absolute values of Sum_{j=1..n} sigma_j * exp(i * Pi * j / n) where sigma_j = +- 1.

1, 1, 1, 2, 3, 4, 8, 12, 16, 33, 62, 67, 186, 316, 280, 1040, 1963, 1702, 6830, 10751, 8679, 45838, 88255, 56292, 264838, 624778, 348817, 2208496, 4526585

Offset

1,4

Links

Table of n, a(n) for n=1..29.

J. M. Borwein, D. M. Bradley and D. J. Broadhurst, Evaluations of k-fold Euler/Zagier sums..., Electron. J. Combinatorics, 4 (No. 2, 1997) #N5.

Crossrefs

Sequence in context: A360363 A133464 A273731 * A228718 A355958 A222123

Adjacent sequences: A013911 A013912 A013913 * A013915 A013916 A013917

Keyword

nonn,nice

Author

David Broadhurst

Extensions

Offset corrected and a(27)-a(29) from Sean A. Irvine, Aug 24 2018

Status

approved