A164649 Numbers n such that sigma(n)/phi(n) = 36/25.

5797, 10153, 20377, 50953, 383719, 405449, 446039, 486421, 608399, 973709, 1321529, 1521311, 3086369, 3228511, 3451877, 3529813, 3859513, 4552373, 4767721, 5827679, 6194321, 6479599, 6724039, 6927893, 7038241, 7919197, 11696111, 15893773, 16894141, 16924873

Offset: 1

Author

M. F. Hasler, Aug 22 2009

Keywords

• nonn

Comments

A subsequence of A011257. See A164646-A164650 for related sequences.

Links

• Donovan Johnson, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000010 (=phi), A000203 (=sigma), A068390 (sigma/phi=4), A163667 (sigma/phi=9), A164646-A164650.

Programs

PARI

for( n=1,1e7, sigma(n)==36/25*eulerphi(n) && print1(n","))

Extensions

More terms from Sean A. Irvine, May 17 2010