

A295012


a(n) = sigma(12n  1)/12, where sigma = sum of divisors (A000203).


1



1, 2, 4, 4, 5, 6, 7, 10, 9, 12, 11, 14, 16, 14, 15, 16, 20, 22, 19, 20, 21, 22, 31, 28, 28, 26, 30, 34, 29, 30, 36, 32, 40, 38, 35, 36, 37, 56, 39, 40, 41, 42, 52, 48, 57, 50, 47, 62, 49, 50, 56, 60, 64, 54, 55, 62, 57, 70, 68, 60, 66, 62, 76, 70, 70, 76
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OFFSET

1,2


COMMENTS

Robert G. Wilson v observes in A280098 that {1, 3, 4, 6, 8, 12, 24} seem to be the only positive integers k such that sigma(kn1)/k is an integer for all n > 0.


LINKS

Muniru A Asiru, Table of n, a(n) for n = 1..100000


MAPLE

with(numtheory):
seq(sigma(12*n1)/12, n=1..10^3); # Muniru A Asiru, Dec 28 2017


MATHEMATICA

Array[DivisorSigma[1, 12 #  1]/12 &, 66] (* Michael De Vlieger, Dec 08 2017 *)


PROG

(PARI) vector(90, n, sigma(12*n1)/12)
(GAP) sequence := List([1..10^5], n> Sigma(12 *n1)/12); # Muniru A Asiru, Dec 28 2017


CROSSREFS

Cf. A280098 (analog for k = 24), A097723 (analog for k = 4), A033686 (analog for k = 3), A000203 (sigma, also the analog for k = 1).
The analog for k = 8 is A258835, up to the offset.
The analog for k = 6 is A098098 (up to the offset), a signed variant of this and the preceding one is A258831.
Sequence in context: A214880 A071193 A071192 * A308629 A100921 A140201
Adjacent sequences: A295009 A295010 A295011 * A295013 A295014 A295015


KEYWORD

nonn


AUTHOR

M. F. Hasler, Dec 08 2017


STATUS

approved



