A213370 a(n) = n AND 2*n, where AND is the bitwise AND operator.

0, 0, 0, 2, 0, 0, 4, 6, 0, 0, 0, 2, 8, 8, 12, 14, 0, 0, 0, 2, 0, 0, 4, 6, 16, 16, 16, 18, 24, 24, 28, 30, 0, 0, 0, 2, 0, 0, 4, 6, 0, 0, 0, 2, 8, 8, 12, 14, 32, 32, 32, 34, 32, 32, 36, 38, 48, 48, 48, 50, 56, 56, 60, 62, 0, 0, 0, 2, 0, 0, 4, 6, 0, 0, 0, 2, 8, 8

Offset: 0

Author

Alex Ratushnyak, Jun 14 2012

Keywords

• nonn
• base
• easy

Links

• Antti Karttunen, Table of n, a(n) for n = 0..16384 (terms 0..1023 from T. D. Noe)
• Index entries for sequences related to binary expansion of n

Crossrefs

Cf. A080099, A213526, A048727, A048735, A269160.

Cf. A003714: indices of 0's.

Cf. A213540: indices of 2's, indices of 4's divided by 2.

Programs

Mathematica

Table[BitAnd[n, 2n], {n, 0, 63}] (* Alonso del Arte, Jun 19 2012 *)

PARI

a(n) = bitand(n, 2*n); \\ Michel Marcus, Mar 26 2021

Python

for n in range(99):
    print(2*n & n, end=", ")

Formula

a(n) = 2 * A048735(n).

a(n) = (1/2)*(A048727(n) XOR A269160(n)) = (n OR 2n) XOR (n XOR 2n). - Antti Karttunen, May 16 2021