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A065549 a(1) = 1; for n > 1, a(n) = 2^((A000043(n) - 1)/2). 3
2, 4, 8, 64, 256, 512, 32768, 1073741824, 17592186044416, 9007199254740992, 9223372036854775808, 1852673427797059126777135760139006525652319754650249024631321344126610074238976 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

Proper subset of A065405.

These values also relate to the sequence of perfect numbers. Every even perfect number except 6 can be written as Sum_{k=1..a(n)} (2*k-1)^3. - Derek Orr, Sep 28 2013

LINKS

Table of n, a(n) for n=2..13.

PROG

(PARI) lista(nn) = {forprime(p=3, nn, if (isprime(2^p-1), print1(2^((p-1)/2), ", ")); ); } \\ Michel Marcus, Aug 04 2016

CROSSREFS

Cf. A000043, A065403, A065404, A065405, A000396.

Sequence in context: A036447 A263451 A069027 * A067507 A068994 A167182

Adjacent sequences:  A065546 A065547 A065548 * A065550 A065551 A065552

KEYWORD

nonn

AUTHOR

Labos Elemer, Nov 13 2001

STATUS

approved

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Last modified February 25 14:43 EST 2018. Contains 299654 sequences. (Running on oeis4.)