

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).


2



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] (*Chandler*)


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



