A213526 a(n) = 3*n AND n, where AND is the bitwise AND operator.

0, 1, 2, 1, 4, 5, 2, 5, 8, 9, 10, 1, 4, 5, 10, 13, 16, 17, 18, 17, 20, 21, 2, 5, 8, 9, 10, 17, 20, 21, 26, 29, 32, 33, 34, 33, 36, 37, 34, 37, 40, 41, 42, 1, 4, 5, 10, 13, 16, 17, 18, 17, 20, 21, 34, 37, 40, 41, 42, 49, 52, 53, 58, 61, 64, 65, 66, 65, 68

Offset: 0

Author

Alex Ratushnyak, Jun 13 2012

Keywords

• nonn
• base
• easy
• look

Comments

Indices of 1's: A007583(n),

indices of 2's: A047849(n+1),

indices of 4's: A039301(n+2),

indices of 5's: A153643(n+3),

indices of 8's: A155701(n+2),

indices of 9's: A155701(n+2)+1 = A163868(n+2),

indices of 10's: A153643(n+4)+3^((n+1) mod 2),

indices of 13's: A039301(n+3)+3,

indices of 16's: A039301(n+3)+4,

indices of 17's: 17, 19, 27, 49, 51, 91, 177, 179, 347, 689, 691, 1371, 2737, 2739, 5467, 10929, 10931, 21851, 43697, 43699, 87387, 174769, 174771, 349531, 699057, 699059, 1398107, 2796209, 2796211, 5592411, 11184817, 11184819, 22369627, 44739249, 44739251, 89478491, ...

indices of 18's: A039301(n+3)+6,

n's such that a(n)<3: A005578, except the first term.

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..10000

Programs

Maple

a:= proc(n) local i, k, m, r;
      k, m, r:= n, 3*n, 0;
      for i from 0 while (m>0 or k>0) do
        r:= r +2^i* irem(m, 2, 'm') *irem(k, 2, 'k')
      od; r
    end:
seq(a(n), n=0..100);  # Alois P. Heinz, Jun 22 2012

Mathematica

Table[BitAnd[n, 3*n], {n, 0, 68}] (* Arkadiusz Wesolowski, Jun 23 2012 *)

PARI

a(n)=bitand(n,3*n) \\ Charles R Greathouse IV, Feb 05 2013

Python

for n in range(99):
    print(3*n & n, end=',')