A114653 - OEIS

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A114653

A114652(n+1) - A114652(n).

1, 2, 1, 3, 2, 6, 2, 7, 1, 10, 3, 10, 4, 8, 7, 15, 7, 18, 6, 13, 9, 22, 8, 20, 8, 19, 9, 28, 6, 29, 11, 22, 11, 26, 10, 34, 13, 25, 11, 40, 10, 42, 16, 24, 15, 45, 13, 43, 12, 31, 18, 50, 16, 42, 19, 38, 23, 57, 12, 58, 24, 38, 24, 46, 18, 65, 24, 43, 15, 68, 19, 71, 28, 37, 26, 66

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OFFSET

1,2

COMMENTS

First occurrence of n: 1, 2, 4, 13, a(5)=??, 6, 8, 14, 21, 10, 31, 49, 20, a(14)=??, 16, 43, a(17)=??, 18, 26, 24, ...,.

LINKS

Table of n, a(n) for n=1..76.

EXAMPLE

Among the first 5 terms of A114652 (1,2,4,5,8) there are 2 terms (1, 5) which are coprime to 6. So a(6) = 2.

MATHEMATICA

a[1] = 1; a[n_] := a[n] = a[n - 1] + Count[GCD[Array[a, n - 1], n], 1]; b = Array[a, 80]; Drop[b, 1] - Drop[b, -1] (* Robert G. Wilson v *)

CROSSREFS