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A053286 Cototient of 2^n +1. 1
1, 1, 3, 1, 13, 17, 45, 1, 189, 225, 685, 257, 2733, 3841, 12969, 1, 43693, 75521, 174765, 61697, 731817, 848897, 2796205, 262145, 13304433, 14802689, 49449609, 15790337, 185023425, 313421825, 715827885, 6701057, 2957312961, 3551128577 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..250

FORMULA

a(n) = A051953(A000051(n)).

MATHEMATICA

Table[2^n + 1 - EulerPhi[2^n + 1], {n, 1, 50}] (* G. C. Greubel, May 31 2018 *)

PROG

(PARI) a(n) = my(x=2^n+1); x - eulerphi(x); \\ Michel Marcus, Aug 17 2017

CROSSREFS

Cf. A000010, A000225, A051953.

Sequence in context: A133171 A133177 A184828 * A008826 A103440 A116483

Adjacent sequences:  A053283 A053284 A053285 * A053287 A053288 A053289

KEYWORD

nonn

AUTHOR

Labos Elemer, Mar 03 2000

STATUS

approved

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Last modified June 25 07:53 EDT 2019. Contains 324347 sequences. (Running on oeis4.)