A246831 a(n) is the concatenation of n and 3n in binary.

0, 7, 22, 57, 76, 95, 210, 245, 280, 315, 350, 737, 804, 871, 938, 1005, 1072, 1139, 1206, 1273, 1340, 1407, 2882, 3013, 3144, 3275, 3406, 3537, 3668, 3799, 3930, 4061, 4192, 4323, 4454, 4585, 4716, 4847, 4978, 5109, 5240, 5371, 5502, 11137, 11396, 11655

Offset: 0

Author

Alois P. Heinz, Sep 04 2014

Keywords

• nonn
• base

Examples

			a(0) = (0|0)_2 = 0.
a(1) = (1|11)_2 = 7.
a(2) = (10|110)_2 = 22.
a(3) = (11|1001)_2 = 57.
a(4) = (100|1100)_2 = 76.
a(5) = (101|1111)_2 = 95.
		

Links

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

Crossrefs

Cf. A246830. Column k=3 of A246834.

Programs

Maple

f:= proc(i, j) local r, h, k; r:=0; h:=0; k:=j;
      while k>0 do r:=r+2^h*irem(k, 2, 'k'); h:=h+1 od; k:=i;
      while k>0 do r:=r+2^h*irem(k, 2, 'k'); h:=h+1 od; r
    end:
a:= n-> f(n, 3*n):
seq(a(n), n=0..60);

Python

def A246831(n):
    return int(bin(n)[2:]+bin(3*n)[2:],2) # Chai Wah Wu, Sep 05 2014

Formula

a(n) = A246830(2n,n).