A075825 a(0) = 1, a(1) = 2; for n>0, a(2n) = |a(n)-a(n-1)|, a(2n+1) = a(n)+a(n-1).

1, 2, 1, 3, 1, 3, 2, 4, 2, 4, 2, 4, 1, 5, 2, 6, 2, 6, 2, 6, 2, 6, 2, 6, 3, 5, 4, 6, 3, 7, 4, 8, 4, 8, 4, 8, 4, 8, 4, 8, 4, 8, 4, 8, 4, 8, 4, 8, 3, 9, 2, 8, 1, 9, 2, 10, 3, 9, 4, 10, 3, 11, 4, 12, 4, 12, 4, 12, 4, 12, 4, 12, 4, 12, 4, 12, 4, 12, 4, 12, 4, 12, 4, 12, 4, 12, 4, 12, 4, 12, 4, 12, 4, 12, 4

Offset: 0

Author

John W. Layman, Oct 14 2002

Keywords

• nonn
• look

Comments

For 2*2^k-2 <= n <= 3*2^k-1, a(n) alternates: 2^floor(k/2) if n is even, A029744(k+2) if n is odd. - Robert Israel, Nov 08 2016

Links

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

Crossrefs

Cf. A029744.

Programs

Maple

A[0]:= 1: A[1]:= 2:
for n from 1 to 100 do
  A[2*n]:= abs(A[n]-A[n-1]);
  A[2*n+1]:= A[n]+A[n-1];
od:
seq(A[n],n=0..201); # Robert Israel, Nov 08 2016

Mathematica

a[0]=1; a[1]=2; a[n_]:=If[EvenQ[n],Abs[a[n/2]-a[n/2-1]],a[(n-1)/2]+a[(n-3)/2]]; Array[a,95,0] (* Stefano Spezia, Apr 04 2024 *)