A062973 Chowla function of n is not divisible by phi(n).

6, 8, 9, 10, 12, 14, 16, 18, 20, 21, 22, 24, 25, 26, 27, 28, 30, 32, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 81, 82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98

Offset

1,1

Comments

Chowla's function (A048050) = sum of divisors of n except 1 and n.

Links

Table of n, a(n) for n=1..70.

Mathematica

okcfQ[n_]:=!Divisible[DivisorSigma[1, n]-n-1, EulerPhi[n]]
Select[Range[100], okcfQ]  (* Harvey P. Dale, Feb 25 2011 *)

Prog

(PARI) j=[]; for(n=1, 400, if(Mod(sigma(n)-n-1, eulerphi(n))!=0, j=concat(j, n))); j

Crossrefs

Sequence in context: A056653 A285847 A231879 * A070162 A030550 A048751

Adjacent sequences: A062970 A062971 A062972 * A062974 A062975 A062976

Keyword

nonn

Author

Jason Earls, Jul 24 2001

Status

approved