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%I #30 Sep 08 2022 08:44:36
%S 63,190,95,286,143,430,215,646,323,970,485,1456,728,364,182,91,274,
%T 137,412,206,103,310,155,466,233,700,350,175,526,263,790,395,1186,593,
%U 1780,890,445,1336,668,334,167,502,251,754,377,1132,566,283,850,425,1276,638,319,958,479,1438,719,2158,1079
%N 3x+1 sequence starting at 63.
%C a(n) = A008875(n - 2) for n > 1.
%C Doesn't reach a power of 2 until a(103) = 16. - _Alonso del Arte_, May 18 2015
%D Richard K. Guy, Unsolved Problems in Number Theory, E16.
%H T. D. Noe, <a href="/A008874/b008874.txt">Table of n, a(n) for n=0..107</a>
%H <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%p f := proc(n) option remember; if n = 0 then 63; elif f(n-1) mod 2 = 0 then f(n-1)/2 else 3*f(n-1)+1; fi; end;
%t NestList[If[EvenQ[#], #/2, 3# + 1] &, 63, 100] (* _Vincenzo Librandi_, Jul 29 2014 *)
%o (Haskell)
%o a008874 n = a008874_list !! n
%o a008874_list = 63 : iterate a006370 63
%o -- _Reinhard Zumkeller_, Aug 30 2012
%o (Magma) [n eq 1 select 63 else IsOdd(Self(n-1)) select 3*Self(n-1)+1 else Self(n-1) div 2: n in [1..70]]; // _Vincenzo Librandi_, Jul 29 2014
%Y Cf. A006370.
%Y Row 63 of A347270.
%K nonn,easy
%O 0,1
%A _N. J. A. Sloane_.
%E More terms from Larry Reeves (larryr(AT)acm.org), Apr 27 2001
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