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A008873 3x+1 sequence starting at 97.

%I A008873 #27 Jul 08 2025 01:21:46
%S A008873 97,292,146,73,220,110,55,166,83,250,125,376,188,94,47,142,71,214,107,
%T A008873 322,161,484,242,121,364,182,91,274,137,412,206,103,310,155,466,233,
%U A008873 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
%N A008873 3x+1 sequence starting at 97.
%D A008873 R. K. Guy, Unsolved Problems in Number Theory, E16.
%H A008873 T. D. Noe, <a href="/A008873/b008873.txt">Table of n, a(n) for n=0..118</a>
%H A008873 <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%p A008873 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;
%t A008873 NestList[If[EvenQ[#], #/2, 3# + 1]&, 97, 100] (* _Vincenzo Librandi_, Jul 29 2014 *)
%o A008873 (Haskell)
%o A008873 a008873 n = a008873_list !! n
%o A008873 a008873_list = 97 : iterate a006370 97
%o A008873 -- _Reinhard Zumkeller_, Aug 30 2012
%o A008873 (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
%Y A008873 Cf. A006370.
%Y A008873 Row 97 of A347270.
%K A008873 nonn
%O A008873 0,1
%A A008873 _N. J. A. Sloane_
%E A008873 More terms from Larry Reeves (larryr(AT)acm.org), Apr 27 2001