

A065915


Numerator of sigma(8*n^2)/sigma(4*n^2).


2



15, 63, 15, 255, 15, 63, 15, 1023, 15, 63, 15, 255, 15, 63, 15, 4095, 15, 63, 15, 255, 15, 63, 15, 1023, 15, 63, 15, 255, 15, 63, 15, 16383, 15, 63, 15, 255, 15, 63, 15, 1023, 15, 63, 15, 255, 15, 63, 15, 4095, 15, 63, 15, 255, 15, 63, 15, 1023, 15, 63, 15, 255, 15, 63
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OFFSET

1,1


COMMENTS

The sequence is not periodic, values of numerators are always 1+2^s.


LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1000


EXAMPLE

sigma(72)/sigma(36) = 15/7.


MATHEMATICA

Table[Numerator[DivisorSigma[1, 8n^2]/DivisorSigma[1, 4n^2]], {n, 70}] (* Harvey P. Dale, Mar 21 2018 *)


PROG

(PARI) for (n=1, 1000, a=numerator(sigma(8*n^2)/sigma(4*n^2)); write("b065915.txt", n, " ", a)) \\ Harry J. Smith, Nov 04 2009
(PARI) a(n)=2^(2*valuation(n, 2)+4)1 \\ Charles R Greathouse IV, Nov 17 2015


CROSSREFS

Cf. A000203.
Sequence in context: A219296 A067572 A066584 * A062965 A157968 A141759
Adjacent sequences: A065912 A065913 A065914 * A065916 A065917 A065918


KEYWORD

nonn,easy


AUTHOR

Labos Elemer, Nov 28 2001


STATUS

approved



