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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 (list; graph; refs; listen; history; text; internal format)
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: A062923 A133464 A273731 * A228718 A222123 A222124

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

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Last modified June 19 11:14 EDT 2019. Contains 324219 sequences. (Running on oeis4.)