A226934 - OEIS

A226934

Numbers k such that tau(2k) | sigma(2k).

3, 7, 10, 11, 15, 19, 21, 22, 23, 27, 28, 30, 31, 33, 34, 35, 39, 43, 46, 47, 48, 51, 55, 57, 58, 59, 63, 66, 67, 69, 70, 71, 75, 77, 79, 82, 83, 84, 87, 91, 92, 93, 94, 95, 99, 102, 103, 105, 106, 107, 110, 111, 112

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

MATHEMATICA

Select[ Range[120], Divisible[ DivisorSigma[1, 2*#], DivisorSigma[0, 2*#]] &] (* Jean-François Alcover, Jul 03 2013 *)

PROG

(PARI) is_a226394(n) = (sigma(2*n, 1) % sigma(2*n, 0) == 0) \\ Michael B. Porter, Jun 27 2013

(Magma) [n: n in [1..120] | IsZero(SumOfDivisors(2*n) mod NumberOfDivisors(2*n))]; // Bruno Berselli, Jun 28 2013

CROSSREFS

Cf. A000005 (tau), A000203 (sigma), A003601, A049642.

Sequence in context: A310177 A324774 A213687 * A238506 A308169 A343225

Adjacent sequences: A226931 A226932 A226933 * A226935 A226936 A226937

KEYWORD

nonn

AUTHOR

Wesley Ivan Hurt, Jun 22 2013

STATUS

approved