A118982 a(1)=1. For m>=0 and 1<=k<=2^m, a(2^m +k) = number of earlier terms of the sequence that are coprime to k.

1, 1, 2, 2, 4, 2, 6, 2, 8, 2, 9, 3, 12, 2, 14, 4, 16, 4, 14, 4, 20, 2, 20, 4, 20, 4, 26, 2, 27, 5, 21, 7, 32, 8, 28, 8, 32, 4, 33, 9, 32, 9, 41, 5, 43, 12, 31, 15, 48, 8, 50, 13, 36, 16, 54, 9, 49, 18, 42, 16, 60, 8, 61, 20, 64, 20, 48, 20, 57, 11, 63, 23, 51, 22, 71, 14, 74, 22, 47, 27

Offset

1,3

Links

Table of n, a(n) for n=1..80.

Example

Since 16 = 2^3 +8, a(16) equals the number of terms among (a(1),a(2),...a(15)) that are coprime to 8. Since the terms 1,1,9 and 3 are the only earlier terms coprime to 8, a(16) = 4.

Maple

A118982 := proc(nmax) local a, m, k, an, i; a := [1] ; m := 0 ; while 2^m <= nmax do for k from 1 to 2^m do an := 0 ; for i from 1 to nops(a) do if gcd(k, a[i]) = 1 then an := an +1 ; fi ; od ; a := [op(a), an] ; od ; m := m+1 ; od ; RETURN(a) ; end: an := A118982(100) : for n from 1 to nops(an) do printf("%d, ", an[n]) ; od ; # R. J. Mathar, Aug 06 2006

Crossrefs

Sequence in context: A137849 A316440 A378637 * A129457 A275365 A119655

Adjacent sequences: A118979 A118980 A118981 * A118983 A118984 A118985

Keyword

nonn

Author

Leroy Quet, May 25 2006

Extensions

More terms from R. J. Mathar, Aug 06 2006

Status

approved