A079071 - OEIS

A079071

Number of numbers < n whose binary representation has the same number of 0's and 1's as n does.

0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 2, 1, 2, 0, 0, 0, 1, 0, 2, 1, 2, 0, 3, 3, 4, 1, 5, 2, 3, 0, 0, 0, 1, 0, 2, 1, 2, 0, 3, 3, 4, 1, 5, 2, 3, 0, 4, 6, 7, 4, 8, 5, 6, 1, 9, 7, 8, 2, 9, 3, 4, 0, 0, 0, 1, 0, 2, 1, 2, 0, 3, 3, 4, 1, 5, 2, 3, 0, 4, 6, 7, 4, 8, 5, 6, 1, 9, 7, 8, 2, 9, 3, 4, 0, 5, 10, 11, 10, 12, 11, 12

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OFFSET

0,13

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..16383

MAPLE

f:= n-> (x-> (t-> t*(t+1)/2+x[2])(x[1]+x[2]))(add(

`if`(i=0, [1, 0], [0, 1]), i=convert(n, base, 2))):

b:= proc(n) b(n):= b(n-1)+x^f(n) end: b(-1):=0:

a:= n-> coeff(b(n-1), x, f(n)):

seq(a(n), n=0..150); # Alois P. Heinz, Feb 08 2018

MATHEMATICA