A215488 a(0)=1, a(n) = a(n-1) + a(2*n AND n), where AND is the bitwise AND operator.

1, 2, 3, 6, 7, 8, 15, 30, 31, 32, 33, 36, 67, 98, 165, 330, 331, 332, 333, 336, 337, 338, 345, 360, 691, 1022, 1353, 1686, 2377, 3068, 5445, 10890, 10891, 10892, 10893, 10896, 10897, 10898, 10905, 10920, 10921, 10922, 10923, 10926, 10957, 10988, 11055, 11220, 22111, 33002

Offset: 0

Author

Alex Ratushnyak, Aug 13 2012

Keywords

• nonn
• base
• easy

Links

• Robert Israel, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A213370.

Programs

Maple

f:= proc(n) option remember;
procname(n-1) + procname(Bits:-And(2*n,n))
end proc:
f(0):= 1:
seq(f(i),i=0..100); # Robert Israel, Dec 29 2016

Mathematica

A215488[n_] := A215488[n] = If[n == 0, 1, A215488[n-1] + A215488[BitAnd[2*n, n]]];
Array[A215488, 50, 0] (* Paolo Xausa, Aug 06 2025 *)

Python

a = [1]*1000
for n in range(1,777):
    print(a[n-1], end=', ')
    a[n]= a[n-1] + a[2*n & n]