A072300 Number of positive integers not exceeding n that are relatively prime to reverse(n).

1, 1, 2, 2, 4, 2, 6, 4, 6, 10, 10, 7, 13, 14, 10, 16, 17, 12, 16, 10, 7, 10, 12, 7, 12, 13, 9, 14, 14, 20, 29, 31, 20, 34, 35, 20, 37, 38, 25, 20, 18, 14, 21, 20, 15, 23, 23, 14, 24, 40, 27, 42, 37, 29, 40, 41, 30, 44, 45, 20, 31, 29, 21, 31, 28, 20, 32, 33, 23, 60, 67, 48, 72

Offset

1,3

Links

Table of n, a(n) for n=1..73.

Example

Among the positive integers not exceeding 12, the seven numbers 1,2,4,5,8,10,11 are relatively prime to reverse(12)=21. Hence a(12)=7.

Mathematica

r = {}; Do[ s = FromDigits[Reverse[IntegerDigits[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

Cf. A000010.

Sequence in context: A063428 A133439 A234649 * A210359 A286553 A278222

Adjacent sequences: A072297 A072298 A072299 * A072301 A072302 A072303

Keyword

base,nonn

Author

Joseph L. Pe, Jul 14 2002

Status

approved