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A129291 1 - 3^(3^n) + 9^(3^n). 1
7, 703, 387400807, 58149737003032434092905183, 196627050475552913618075908526912116282660024455971729157367165907347241304007 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

a(n) is the ratio of two consecutive base 3 Fermat numbers A129290(n) = 3^(3^n) + 1 = {4, 28, 19684, 7625597484988, ...}.

LINKS

Table of n, a(n) for n=0..4.

FORMULA

a(n) = A002061(3^(3^n)). a(n) = A129290(n+1) / A129290(n).

MATHEMATICA

Table[1 - 3^3^n + 9^3^n, {n, 0, 5}]

CROSSREFS

Cf. A129290 = 3^(3^n) + 1. Cf. A055777 = 3^(3^n). Cf. A002061 = Central polygonal numbers: n^2 - n + 1.

Sequence in context: A261696 A174855 A186160 * A229149 A159815 A070746

Adjacent sequences:  A129288 A129289 A129290 * A129292 A129293 A129294

KEYWORD

nonn

AUTHOR

Alexander Adamchuk, Apr 08 2007

STATUS

approved

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Last modified December 9 19:51 EST 2019. Contains 329879 sequences. (Running on oeis4.)