

A062972


Numbers k such that the Chowla function of k is divisible by phi(k).


4



1, 2, 3, 4, 5, 7, 11, 13, 15, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269
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OFFSET

1,2


COMMENTS

Chowla's function (A048050) = sum of divisors of n except 1 and n.
Sequence contains all primes; see A070037 for nonprime terms.  Charles R Greathouse IV, Apr 14 2010


LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000


MATHEMATICA

chowla[1] = 0; chowla[n_] := DivisorSigma[1, n]  n  1; Select[Range[270], Divisible[chowla[#], EulerPhi[#]] &] (* Amiram Eldar, Dec 01 2019 *)


PROG

(PARI) j=[]; for(n=1, 600, if(Mod(sigma(n)n1, eulerphi(n)) == 0, j=concat(j, n))); j


CROSSREFS

Cf. A000010, A048050, A070037.
Sequence in context: A234719 A055464 A139316 * A231878 A285304 A036844
Adjacent sequences: A062969 A062970 A062971 * A062973 A062974 A062975


KEYWORD

nonn,changed


AUTHOR

Jason Earls, Jul 24 2001


STATUS

approved



