A008873 3x+1 sequence starting at 97.

97, 292, 146, 73, 220, 110, 55, 166, 83, 250, 125, 376, 188, 94, 47, 142, 71, 214, 107, 322, 161, 484, 242, 121, 364, 182, 91, 274, 137, 412, 206, 103, 310, 155, 466, 233, 700, 350, 175, 526, 263, 790, 395, 1186, 593, 1780, 890, 445, 1336, 668, 334, 167, 502, 251, 754, 377, 1132, 566, 283, 850, 425

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

References

• R. K. Guy, Unsolved Problems in Number Theory, E16.

Links

• T. D. Noe, Table of n, a(n) for n=0..118
• Index entries for sequences related to 3x+1 (or Collatz) problem

Crossrefs

Cf. A006370.

Row 97 of A347270.

Programs

Haskell

a008873 n = a008873_list !! n
a008873_list = 97 : iterate a006370 97
-- Reinhard Zumkeller, Aug 30 2012

Magma

[n eq 1 select 97 else IsOdd(Self(n-1)) select 3*Self(n-1)+1 else Self(n-1) div 2: n in [1..80]]; // Vincenzo Librandi, Jul 29 2014

Maple

f := proc(n) option remember; if n = 0 then 97; elif f(n-1) mod 2 = 0 then f(n-1)/2 else 3*f(n-1)+1; fi; end;

Mathematica

NestList[If[EvenQ[#], #/2, 3# + 1]&, 97, 100] (* Vincenzo Librandi, Jul 29 2014 *)

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Apr 27 2001