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

0,2

Links

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

Formula

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

Example

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

Prog

(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

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.

Sequence in context: A162276 A261955 A144615 * A105802 A285844 A285948

Adjacent sequences: A088695 A088696 A088697 * A088699 A088700 A088701

Keyword

nonn,easy,base

Author

Ralf Stephan, Oct 07 2003

Status

approved