A088698 Replace 1 with 11 in binary representation of n.

0, 3, 6, 15, 12, 27, 30, 63, 24, 51, 54, 111, 60, 123, 126, 255, 48, 99, 102, 207, 108, 219, 222, 447, 120, 243, 246, 495, 252, 507, 510, 1023, 96, 195, 198, 399, 204, 411, 414, 831, 216, 435, 438, 879, 444, 891, 894, 1791, 240, 483, 486, 975, 492, 987, 990

Offset: 0

Author

Ralf Stephan, Oct 07 2003

Keywords

• nonn
• easy
• base

Examples

			n=9: 1001 -> 110011 = 51, so a(9) = 51.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 0..8192

Crossrefs

Ordered terms plus one are in A048297.

Same sequence sorted into ascending order: A277335, A290258 (without 0).

Cf. A001196, A084471, A048678, A088697.

Main diagonal of A341520, right edge of A341521.

Programs

PARI

a(n)=if(n<1,0,if(n%2==0,2*a(n/2),4*a((n-1)/2)+3))

Python

def a(n): return int(bin(n)[2:].replace('1', '11'), 2)
print([a(n) for n in range(55)]) # Michael S. Branicky, Feb 20 2021

Formula

a(0)=0, a(2n) = 2a(n), a(2n+1) = 4a(n) + 3.