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A013914
Number of distinct nonzero absolute values of Sum_{j=1..n} sigma_j * exp(i * Pi * j / n) where sigma_j = +- 1.
0
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
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
KEYWORD
nonn,nice
EXTENSIONS
Offset corrected and a(27)-a(29) from Sean A. Irvine, Aug 24 2018
STATUS
approved