A108732 a(0)=22; if n odd, a(n) = a(n-1)/2, otherwise a(n) = 4*a(n-1).

22, 11, 44, 22, 88, 44, 176, 88, 352, 176, 704, 352, 1408, 704, 2816, 1408, 5632, 2816, 11264, 5632, 22528, 11264, 45056, 22528, 90112, 45056, 180224, 90112, 360448, 180224, 720896, 360448, 1441792, 720896

Offset: 0

Author

Alexandre Wajnberg & Guadalupe Garcia, Jun 22 2005

Keywords

• easy
• nonn

Comments

A108213 is a subsequence of this sequence and is also twice this sequence.

Links

• Harvey P. Dale, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (0,2)

Crossrefs

Cf. A005015, A108213.

Programs

Mathematica

nxt[{n_,a_}]:={n+1,If[EvenQ[n],a/2,4a]}; NestList[nxt,{0,22},40][[All,2]] (* or *) LinearRecurrence[{0,2},{22,11},40] (* Harvey P. Dale, Jul 22 2021 *)

Formula

a(2n+1) = a(2n-2).

Recurrence: a(n) = 2a(n-2), a(0)=22, a(1)=11. G.f.: (22x+44)/(1-2x^2). - Ralf Stephan, Jul 16 2013

a(n) = 11 * 2^A028242(n). - Franklin T. Adams-Watters, Mar 29 2006