A253608 The binary representation of a(n) is the concatenation of n and the binary complement of n, A035327(n).

2, 9, 12, 35, 42, 49, 56, 135, 150, 165, 180, 195, 210, 225, 240, 527, 558, 589, 620, 651, 682, 713, 744, 775, 806, 837, 868, 899, 930, 961, 992, 2079, 2142, 2205, 2268, 2331, 2394, 2457, 2520, 2583, 2646, 2709, 2772, 2835, 2898, 2961, 3024, 3087, 3150, 3213

Offset: 1

Author

Alex Ratushnyak, Jan 05 2015

Keywords

• nonn
• easy
• base

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A035327, A036044, A070939.

Programs

Maple

a:= n-> (n+1)*(2^(ilog2(n)+1)-1):
seq(a(n), n=1..50);  # Alois P. Heinz, Jan 08 2015

Mathematica

Array[(# + 1) (2^(Floor@ Log2[#] + 1) - 1) &, 50] (* Michael De Vlieger, Oct 13 2018 *)

PARI

a(n) = (n+1)*(2^#binary(n)-1); \\ Michel Marcus, Jan 08 2015

Python

for n in range(1,333):
  print(str((n+1)*(2 ** int.bit_length(int(n))-1)), end=',')

Formula

a(n) = (n+1) * (2^BL(n) - 1), where BL(n) is the binary length of n.