A123755 - OEIS

A123755

a(0)=1. a(n) = number of earlier terms which are divisible by (the number of 1's in the binary representation of n).

1, 1, 2, 1, 4, 2, 3, 1, 8, 4, 5, 1, 5, 1, 1, 3, 16, 6, 7, 3, 7, 4, 4, 6, 10, 5, 5, 6, 6, 6, 6, 5, 32, 16, 17, 9, 17, 10, 10, 8, 20, 10, 10, 10, 10, 10, 10, 15, 27, 12, 13, 11, 13, 11, 11, 16, 13, 12, 13, 16, 14, 16, 16, 8, 64, 36, 37, 15, 37, 16, 16, 21, 39, 18, 19, 21, 20, 22, 22, 18, 44

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..80.

EXAMPLE

9 in binary is 1001, which has 2 ones. So a(9) is the number of terms, from a(0) to a(8), which are divisible by 2. a(2)=2, a(4)=4, a(5)=2 and a(8)=8 are the four earlier terms divisible by 2. So a(9) = 4.

MATHEMATICA

f[l_List] := Append[l, Count[Mod[l, Plus @@ IntegerDigits[Length[l], 2]], 0]]; Nest[f, {1}, 80] (* Ray Chandler, Oct 16 2006 *)

CROSSREFS

Cf. A123756, A123757.

Sequence in context: A007733 A128520 A269370 * A118291 A118290 A208569

Adjacent sequences: A123752 A123753 A123754 * A123756 A123757 A123758

KEYWORD

easy,nonn

AUTHOR

Leroy Quet, Oct 12 2006

EXTENSIONS

Extended by Ray Chandler, Oct 16 2006

STATUS

approved