A037238 5x - 1 sequence starting at 19 (a(n+1) = a(n)/2 if a(n) is even, or 5*a(n)-1 if a(n) is odd).

19, 94, 47, 234, 117, 584, 292, 146, 73, 364, 182, 91, 454, 227, 1134, 567, 2834, 1417, 7084, 3542, 1771, 8854, 4427, 22134, 11067, 55334, 27667, 138334, 69167, 345834, 172917, 864584, 432292, 216146, 108073, 540364, 270182, 135091, 675454, 337727

Offset

1,1

Comments

Reaches 4, 2, 1, 4, 2, 1, ... in 437 steps. - T. D. Noe, Mar 01 2008

Links

T. D. Noe, Table of n, a(n) for n=1..437

Mathematica

NestList[If[EvenQ[#], #/2, 5# - 1] &, 19, 100] (* Alonso del Arte, Nov 19 2020 *)

Prog

(Scala) def fiveX(n: Int): Int = n % 2 match {
  case 0 => n / 2
  case _ => 5 * n - 1
}
val A037238 = LazyList.iterate(19)(fiveX)
A037238.take(100).toList // Alonso del Arte, Nov 19 2020

Crossrefs

Cf. A090691.

Sequence in context: A118294 A157098 A371532 * A109513 A173368 A041696

Adjacent sequences: A037235 A037236 A037237 * A037239 A037240 A037241

Keyword

nonn,easy

Author

Dan Goldwater (dan(AT)craftech.com)

Extensions

More terms from Erich Friedman.

Definition clarified by N. J. A. Sloane, Sep 14 2024

Status

approved