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A198915 a(n) = 1 - 2^k + 4^k where k = 3^n. 1
3, 57, 261633, 18014398375264257, 5846006549323611672814736913013492849365380759553 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..6

D. Alpern, Factors of Generalized Fermat Numbers

MAPLE

A198915:=n->4^(3^n) - 2^(3^n) + 1: seq(A198915(n), n=0..6); # Wesley Ivan Hurt, May 03 2017

MATHEMATICA

Table[4^(3^n) - 2^(3^n) + 1, {n, 0, 5}]

PROG

(PARI) a(n)=1<<(2*3^n)-1<<3^n+1 \\ Charles R Greathouse IV, Oct 31 2011

(MAGMA) [4^(3^n) - 2^(3^n) + 1: n in [0..7]]; // Vincenzo Librandi, Jun 29 2014

CROSSREFS

Cf. A051154.

Sequence in context: A127263 A134723 A133060 * A037107 A335293 A041735

Adjacent sequences:  A198912 A198913 A198914 * A198916 A198917 A198918

KEYWORD

nonn,easy

AUTHOR

Artur Jasinski, Oct 31 2011

STATUS

approved

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Last modified October 18 03:25 EDT 2021. Contains 348065 sequences. (Running on oeis4.)