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A008882 3x+1 sequence starting at 99.

%I A008882 #37 Jul 08 2025 01:22:24
%S A008882 99,298,149,448,224,112,56,28,14,7,22,11,34,17,52,26,13,40,20,10,5,16,
%T A008882 8,4,2,1,4,2,1,4,2,1,4,2,1,4,2,1,4,2,1,4,2,1,4,2,1,4,2,1,4,2,1,4,2,1,
%U A008882 4,2,1,4,2,1,4,2,1,4,2,1,4
%N A008882 3x+1 sequence starting at 99.
%D A008882 R. K. Guy, Unsolved Problems in Number Theory, E16.
%H A008882 Vincenzo Librandi, <a href="/A008882/b008882.txt">Table of n, a(n) for n = 0..200</a>
%H A008882 <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%H A008882 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,1).
%p A008882 f := proc(n) option remember; if n = 0 then 99; elif f(n-1) mod 2 = 0 then f(n-1)/2 else 3*f(n-1)+1; fi; end;
%t A008882 NestList[If[EvenQ[#],#/2,3#+1]&,99,70] (* _Harvey P. Dale_, Jul 28 2014 *)
%o A008882 (Magma) [n eq 1 select 99 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
%o A008882 (PARI) Collatz(n,lim=0)={
%o A008882 my(c=n,e=0,L=List(n)); if(lim==0, e=1; lim=n*10^6);
%o A008882 for(i=1,lim, if(c%2==0, c=c/2, c=3*c+1); listput(L,c); if(e&&c==1, break));
%o A008882 return(Vec(L)); }
%o A008882 print(Collatz(99,60)) \\ A008882 (from 99 first 60)
%o A008882 \\ _Anatoly E. Voevudko_, Mar 26 2016
%Y A008882 Row 99 of A347270.
%K A008882 nonn,easy
%O A008882 0,1
%A A008882 _N. J. A. Sloane_