A055510 Largest odd prime in sequence obtained in 3x+1 (or Collatz) problem starting at n, or 0 if no such prime is found.

0, 0, 5, 0, 5, 5, 17, 0, 17, 5, 17, 5, 13, 17, 53, 0, 17, 17, 29, 5, 0, 17, 53, 5, 29, 13, 1619, 17, 29, 53, 1619, 0, 29, 17, 53, 17, 37, 29, 101, 5, 1619, 0, 43, 17, 17, 53, 1619, 5, 37, 29, 29, 13, 53, 1619, 1619, 17, 43, 29, 101, 53, 61, 1619, 1619, 0, 37, 29, 101, 17, 13

Offset

1,3

Links

Table of n, a(n) for n=1..69.

Eric Weisstein's World of Mathematics, Collatz Problem

Index entries for sequences related to 3x+1 (or Collatz) problem

Mathematica

op[n_]:=Module[{lst=NestWhileList[If[EvenQ[#], #/2, 3#+1]&, n, #!=1&], m}, m= Max[Select[ lst, PrimeQ]]; If[m<3, 0, m]]; Array[op, 70] {* Harvey P. Dale, Apr 30 2011 *)

Crossrefs

Cf. A055509, A087272.

Sequence in context: A144702 A238192 A156716 * A200397 A265302 A228764

Adjacent sequences: A055507 A055508 A055509 * A055511 A055512 A055513

Keyword

nonn

Author

G. L. Honaker, Jr., Jun 30 2000

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Aug 09 2001

Status

approved