

A107754


Number of subsets of the nth roots of unity that sum to 1.


7



1, 1, 1, 2, 1, 6, 1, 8, 4, 18, 1, 60, 1, 66, 20, 128, 1, 600, 1, 612, 68, 1026, 1, 6000, 16, 4098, 256, 8580, 1, 95226, 1, 32768
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OFFSET

1,4


LINKS

Table of n, a(n) for n=1..32.


FORMULA

For prime p, a(p^i) = 2^(p^(i1)1).


MATHEMATICA

<< DiscreteMath`Combinatorica`; f[n_] := Plus @@ Table[ Count[ KSubsets[ Range[n], k], q_List /; Chop[ 1 + Plus @@ (E^((2.*Pi*I*q)/n))] === 0], {k, 0, n}]; Table[ f[n], {n, 24}] (* Robert G. Wilson v, Jun 03 2005 *)


CROSSREFS

Cf. A103314 (number of subsets of the nth roots of unity summing to zero) and A108417 (number of subsets of the nth roots of unity summing to the absolute value of 1).
Sequence in context: A324193 A264859 A007956 * A181569 A274085 A302129
Adjacent sequences: A107751 A107752 A107753 * A107755 A107756 A107757


KEYWORD

nonn,more


AUTHOR

T. D. Noe, May 23 2005


STATUS

approved



