A162880 Numbers k such that tau(sigma(k)) is not equal to sigma(tau(k)).

2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 45, 46, 47, 48, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 67, 69, 71, 72, 73, 74, 75, 77, 78, 79, 80

Offset: 1

Author

Jaroslav Krizek, Jul 16 2009

Keywords

• nonn

Comments

The complement of A076361, that is, the indices k where A076360(k) is not zero.

Examples

			a(6)= 8 is in the list because tau(sigma(8))=A062068(8)=4 whereas sigma(tau(8)) = A062069(8) = 7.
		

Crossrefs

Cf. A000005, A000203, A076361, A076360.

Programs

PARI

is(n)=numdiv(sigma(n))!=sigma(numdiv(n)) \\ Charles R Greathouse IV, Jun 25 2013

Extensions

Edited by R. J. Mathar, Jul 21 2009