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A051156 a(n) = (2^p^2-1)/(2^p-1) where p is the n-th prime. 7
5, 73, 1082401, 4432676798593, 1298708349570020393652962442872833, 91355004067076339167413824240109498970069278721, 7588608256743087977590500540116743445925584618982806531428980886590618779326218241 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Note that a(n) = Phi(p,2^p) or a(n) = Phi(p^2,2), where Phi(m,x) is the m-th cyclotomic polynomial and p is the n-th prime. - Thomas Ordowski, Feb 18 2014

LINKS

Table of n, a(n) for n=1..7.

FORMULA

a(n) = A070526(prime(n)), a(n) = A019320(prime(n)^2). - Thomas Ordowski, Feb 18 2014

MATHEMATICA

Table[Cyclotomic[Prime[n]^2, 2], {n, 7}] (* Arkadiusz Wesolowski, May 13 2012 *)

CROSSREFS

Cf. A051154, A051155, A051157.

Sequence in context: A012640 A128889 A131958 * A092826 A065894 A233013

Adjacent sequences:  A051153 A051154 A051155 * A051157 A051158 A051159

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified February 19 20:17 EST 2019. Contains 320328 sequences. (Running on oeis4.)