A068915 a(n) = n if n<2; a(n) = |a(n/2)-a(n/2-1)| if n is even, and a(n) = a((n-1)/2) + a((n-1)/2+1) if n is odd.

0, 1, 1, 2, 0, 3, 1, 2, 2, 3, 3, 4, 2, 3, 1, 4, 0, 5, 1, 6, 0, 7, 1, 6, 2, 5, 1, 4, 2, 5, 3, 4, 4, 5, 5, 6, 4, 7, 5, 6, 6, 7, 7, 8, 6, 7, 5, 8, 4, 7, 3, 6, 4, 5, 3, 6, 2, 7, 3, 8, 2, 7, 1, 8, 0, 9, 1, 10, 0, 11, 1, 10, 2, 11, 3, 12, 2, 11, 1, 12, 0, 13, 1, 14, 0, 15, 1, 14, 2, 13, 1, 12, 2, 13, 3, 12, 4, 11, 3, 10, 4, 9, 3, 10, 2, 9, 1, 8, 2, 9, 3, 8, 4, 9, 5, 10, 4, 11, 5, 10

Offset

0,4

Links

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

Example

a(2) = |1-0| = 1, a(3) = 1+1 = 2, a(4) = |1-1| = 0, a(5) = 1+2 = 3.

Maple

a:= proc(n) option remember;
      if n<2 then n
    elif irem (n, 2)=0 then abs(a(n/2)-a(n/2-1))
    else a((n-1)/2)+a((n-1)/2+1)
      fi
    end:
seq (a(n), n=0..119);

Mathematica

a[n_] := a[n] = If[n<2, n, If[EvenQ[n], Abs[a[n/2] - a[n/2-1]], a[(n-1)/2] + a[(n-1)/2 + 1]]];
a /@ Range[0, 119] (* Jean-François Alcover, Nov 17 2020 *)

Crossrefs

Sequence in context: A080096 A322978 A294142 * A302193 A133925 A071492

Adjacent sequences: A068912 A068913 A068914 * A068916 A068917 A068918

Keyword

easy,nonn

Author

Aaron K. Johnson (akj(AT)21stcentury.net), Mar 06 2002

Extensions

Edited by Alois P. Heinz, Feb 04 2011

Status

approved