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A068531 a(n) = (3^(2^n) - 1)/2^(n + 2). 5
1, 5, 205, 672605, 14476720225405, 13412827423017626893194723005, 23027704253395670256876704807446325518902757016163752166205, 135750441774555403090761510536778616322479346492704236319926586357457102177506285098634540189560165548644204629442284605 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Every element of this sequence is an odd number (see link). - Graeme McRae, Jan 12 2005

LINKS

Table of n, a(n) for n=1..8.

Graeme McRae, Proof: for every positive integer k, there exists a positive integer m such that 3^m+5 is divisible by 2^k.

CROSSREFS

Cf. A090129.

Sequence in context: A005333 A162087 A292330 * A144139 A020541 A006413

Adjacent sequences:  A068528 A068529 A068530 * A068532 A068533 A068534

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Mar 22 2002

STATUS

approved

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Last modified December 13 22:48 EST 2019. Contains 329974 sequences. (Running on oeis4.)