A063043 Collatz-2 (A063041) trajectory starting at 17.

17, 222, 111, 37, 1148, 574, 287, 41, 1518, 759, 253, 23, 438, 219, 73, 5184, 2592, 1296, 648, 324, 162, 81, 27, 9, 3, 7, 36, 18, 9, 3, 7, 36, 18, 9, 3, 7, 36, 18, 9, 3, 7, 36, 18, 9, 3, 7, 36, 18, 9, 3, 7, 36, 18, 9, 3, 7, 36, 18, 9, 3, 7, 36, 18, 9, 3, 7, 36

Offset: 0

Author

Reinhard Zumkeller, Jul 07 2001

Keywords

• easy
• nonn

Comments

a(23) = a(28) = 9 and a(i) = a(j) <==> i = j for i, j < 28; same cycle values as A063042 but the conjecture that this is the only cycle for all starting values is not true: see A063044

Crossrefs

Cf. A063041, A063042, A063044.

Programs

Mathematica

NestList[If[PrimeQ[#],#*Prime[PrimePi[#]-1]+1,#/Min@@First/@FactorInteger[#]]&,17,30] (* Jayanta Basu, May 27 2013 *)

Formula

a(0) = 17 and a(n) = A063041(a(n-1)) for n > 0

Extensions

More terms from Sean A. Irvine, Apr 16 2023