A046640 a(n) = A045763(n) + 1.

1, 1, 1, 1, 1, 2, 1, 2, 2, 4, 1, 4, 1, 6, 5, 5, 1, 8, 1, 8, 7, 10, 1, 10, 4, 12, 7, 12, 1, 16, 1, 12, 11, 16, 9, 17, 1, 18, 13, 18, 1, 24, 1, 20, 17, 22, 1, 24, 6, 26, 17, 24, 1, 30, 13, 26, 19, 28, 1, 34, 1, 30, 23, 27, 15, 40, 1, 32

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Comments

a(n) = number of nondivisors in the cototient of n, including 1. - Michael De Vlieger, Feb 25 2018

Links

• Antti Karttunen, Table of n, a(n) for n = 1..65537

Crossrefs

Cf. A000005, A000010, A045763.

Programs

Mathematica

Table[Count[Range@ n, _?(And[! CoprimeQ[#, n], ! Divisible[n, #]] &)] + 1, {n, 68}] (* or *)
Array[2 + # - (DivisorSigma[0, #] + EulerPhi[#]) &, 68] (* Michael De Vlieger, Feb 25 2018 *)

PARI

A046640(n) = (2+n-numdiv(n)-eulerphi(n)); \\ Antti Karttunen, Feb 25 2018, after Charles R Greathouse IV's program for A045763.

Formula

a(n) = 2 + n - A000005(n) - A000010(n). - Antti Karttunen, Feb 25 2018

Extensions

Offset corrected by Antti Karttunen, Feb 25 2018