A068400 Numbers k such that sigma(k) = phi(k*bigomega(k)).

248, 357, 1045, 3596, 3956, 4064, 5396, 8636, 20026, 20320, 23374, 24871, 25714, 29029, 33915, 35074, 39585, 41656, 50065, 55154, 56134, 56536, 58435, 61344, 64285, 74613, 79000, 87087, 87685, 137885, 140335, 142240, 353133, 383656, 393104, 423657, 474548, 479864

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..1000

Example

248 = 31*2^3 is here because sigma(248) = 480 = eulerphi(248*bigomega(2^3 * 31)) = eulerphi(248*4). - David A. Corneth, Jun 29 2025

Prog

(PARI) isok(k) = {my(f = factor(k)); sigma(f) == eulerphi(k * bigomega(f)); } \\ Amiram Eldar, May 09 2025

Crossrefs

Cf. A000010 (phi), A000203 (sigma), A001222 (bigomega), A074891.

Sequence in context: A187398 A065146 A064977 * A240967 A230856 A109478

Adjacent sequences: A068397 A068398 A068399 * A068401 A068402 A068403

Keyword

nonn

Author

Benoit Cloitre, Mar 02 2002

Status

approved