A073567 Numbers k such that sigma(k) = phi(k)*omega(k).

35, 357, 3135, 3339, 5049, 20026, 23374, 25714, 33915, 35074, 35343, 39105, 39585, 55154, 56134, 71145, 124605, 157586, 316274, 317205, 373065, 423045, 435435, 474548, 479655, 559845, 596666, 604012, 696514, 711988, 819772, 1123605, 1161508, 1277788, 1491412

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Donovan Johnson)

Mathematica

t = {}; Do[If[DivisorSigma[1, n] == EulerPhi[n]*PrimeNu[n], AppendTo[t, n]], {n, 700000}]; t (* Jayanta Basu, Jul 01 2013 *)
Select[Range[15*10^5], DivisorSigma[1, #]==EulerPhi[#]PrimeNu[#]&] (* Harvey P. Dale, Mar 04 2023 *)

Prog

(PARI) for(n=1, 10000000, if(sigma(n)==eulerphi(n)*omega(n), print1(n, ", "))) \\ Lambert Klasen, Feb 20 2005
(PARI) isok(k) = {my(f = factor(k)); sigma(f) == eulerphi(f)*omega(f); } \\ Amiram Eldar, May 04 2025

Crossrefs

Subsequence of A020492.

Cf. A000010 (phi), A000203 (sigma), A001221 (omega).

Sequence in context: A101099 A027803 A267749 * A225697 A133458 A380581

Adjacent sequences: A073564 A073565 A073566 * A073568 A073569 A073570

Keyword

nonn

Author

Benoit Cloitre, Aug 31 2002

Extensions

More terms from Lambert Klasen (lambert.klasen(AT)gmx.de), Dec 23 2004

Status

approved