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 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. 0

%I

%S 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 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 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 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 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 (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 Cf. A080825.

%K easy,nonn,tabf

%O 1,2

%A _Cino Hilliard_, Apr 16 2003

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Last modified October 31 11:50 EDT 2020. Contains 338101 sequences. (Running on oeis4.)