A072301 Number of positive integers not exceeding n that are relatively prime to sigma(n).

1, 2, 2, 4, 2, 2, 4, 5, 9, 3, 4, 5, 6, 5, 5, 16, 6, 11, 8, 6, 11, 7, 8, 7, 25, 8, 11, 12, 8, 10, 16, 19, 11, 11, 12, 29, 18, 10, 17, 10, 12, 14, 20, 13, 14, 15, 16, 23, 31, 33, 17, 22, 18, 15, 19, 15, 23, 15, 16, 17, 30, 21, 30, 64, 19, 22, 32, 20, 23, 23, 24, 35, 36, 24, 37, 26, 26

Offset

1,2

Links

Table of n, a(n) for n=1..77.

Example

Among the positive integers not exceeding 12, the five numbers 1,3,5,9,11 are relatively prime to sigma(12)=28. Hence a(12)=5.

Mathematica

r = {}; Do[ s = DivisorSigma[1, n]; j = 0; For[i = 1, i <= n, i++, If[GCD[s, i] == 1, j++ ]]; r = Append[r, j], {n, 1, 10^2}]; r

Crossrefs

Sequence in context: A309709 A143230 A276604 * A127171 A215655 A118232

Adjacent sequences: A072298 A072299 A072300 * A072302 A072303 A072304

Keyword

base,nonn

Author

Joseph L. Pe, Jul 14 2002

Status

approved