cp's OEIS Frontend

A081169 Triangle in which n-th row gives trajectory of n (including n itself) under the map x -> x/2 if x is even, x -> 3*x-1 if x is odd, stopping when reaching 1, 5 or 17.

%I A081169 #4 Oct 01 2013 17:57:36
%S A081169 1,2,1,2,1,3,8,4,2,1,4,2,1,5,14,7,20,10,5,6,3,8,4,2,1,7,20,10,5,8,4,2,
%T A081169 1,9,26,13,38,19,56,28,14,7,20,10,5,10,5,11,32,16,8,4,2,1,12,6,3,8,4,
%U A081169 2,1,13,38,19,56,28,14,7,20,10,5,14,7,20,10,5,15,44,22,11,32,16,8,4,2,1,16
%N A081169 Triangle in which n-th row gives trajectory of n (including n itself) under the map x -> x/2 if x is even, x -> 3*x-1 if x is odd, stopping when reaching 1, 5 or 17.
%C A081169 It is conjectured that the sequence will always end in one of three loops: 1, 2,1,1, ...; 5 14 7 20 10 5...; or 17 50 25 74 37 110 55 164 82 41 122 61 182 91 272 136 68 34 17...
%o A081169 (PARI) xnm3(n) = { print1(1" "2" "1" "); for(x=2,n, x1=x; print1(x1" "); while(x1>1, if(x1%2==0,x1/=2,x1 = 3*p-1); print1(x1" "); if(x1==5 || x1==17,break); ) ) }
%Y A081169 Cf. A080825.
%K A081169 easy,nonn,tabf
%O A081169 1,2
%A A081169 _Cino Hilliard_, Apr 16 2003