A033967 Trajectory of 1 under map n->21n+1 if n odd, n->n/2 if n even.

1, 22, 11, 232, 116, 58, 29, 610, 305, 6406, 3203, 67264, 33632, 16816, 8408, 4204, 2102, 1051, 22072, 11036, 5518, 2759, 57940, 28970, 14485, 304186, 152093, 3193954, 1596977, 33536518, 16768259, 352133440, 176066720, 88033360, 44016680, 22008340, 11004170

Offset

0,2

Links

Table of n, a(n) for n=0..36.

Maple

a:= proc(n) option remember; `if`(n=0, 1,
      (t-> `if`(t::odd, 21*t+1, t/2))(a(n-1)))
    end:
seq(a(n), n=0..36);  # Alois P. Heinz, Jun 24 2025

Mathematica

NestList[If[OddQ[#], 21#+1, #/2]&, 1, 30] (* Harvey P. Dale, Aug 24 2012 *)

Crossrefs

Cf. A037108.

Sequence in context: A102612 A040465 A108732 * A262244 A140872 A133724

Adjacent sequences: A033964 A033965 A033966 * A033968 A033969 A033970

Keyword

nonn

Author

N. J. A. Sloane

Status

approved