A259193 - OEIS

%I #23 Sep 08 2022 08:46:13

%S 11,56,28,14,7,36,18,9,46,23,116,58,29,146,73,366,183,916,458,229,

%T 1146,573,2866,1433,7166,3583,17916,8958,4479,22396,11198,5599,27996,

%U 13998,6999,34996,17498,8749,43746,21873,109366,54683,273416,136708,68354,34177,170886,85443

%N 5x + 1 sequence beginning at 11.

%H Alonso del Arte, <a href="/A259193/b259193.txt">Table of n, a(n) for n = 0..999</a>

%H Alex V. Kontorovich & Jeffrey C. Lagarias, <a href="http://arxiv.org/abs/0910.1944">Stochastic Models for the 3x+1 and 5x+1 Problems</a> arXiv:0910.1944 [math.NT], 2009.

%F a(0) = 11; a(n) = 5a(n - 1) + 1 if a(n - 1) is odd, a(n) = a(n - 1)/2 otherwise.

%e 11 is odd, so it's followed by 5 * 11 + 1 = 56.

%e 56 is even, so it's followed by 56/2 = 28.

%t NestList[If[EvenQ[#], #/2, 5# + 1] &, 5, 100]

%o (Magma) [n eq 1 select 11 else IsOdd(Self(n-1)) select 5*Self(n-1)+1 else Self(n-1) div 2: n in [1..80]]; // _Vincenzo Librandi_, Jul 04 2015

%Y Cf. A259207, A057688.

%K nonn,easy

%O 0,1

%A _Alonso del Arte_, Jun 21 2015