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A135727
Maximal value in orbit of n under the map A001281(x)=3x-1 if x odd, x/2 if x even.
5
0, 2, 2, 8, 4, 20, 8, 20, 8, 56, 20, 32, 12, 56, 20, 44, 16, 272, 56, 56, 20, 272, 32, 272, 24, 272, 56, 80, 28, 128, 44, 272, 32, 488, 272, 104, 56, 272, 56, 128, 40, 272, 272, 128, 44, 272, 272, 140, 48, 488, 272
OFFSET
0,2
COMMENTS
On the set of positive integers, the orbit of any number under A001281 seems to end in the orbit of 2, of 20 or of 272, which are the respective maxima of these cycles. Since any odd number increases under the map A001281, all elements of this sequence are even.
PROG
(PARI) A135727(n)=local(m=n); if(n, while( n != 272 & n != 20 & n != 2, if( n%2, n=3*n-1; m=max(n, m), n>>=1))); m
KEYWORD
nonn
AUTHOR
M. F. Hasler, Nov 26 2007
STATUS
approved