A080825 Triangle read by rows in which n-th row gives trajectory of n (omitting n itself) under the map k -> k-1 if k odd, k -> k/2 if k even.
1, 2, 1, 2, 1, 4, 2, 1, 3, 2, 1, 6, 3, 2, 1, 4, 2, 1, 8, 4, 2, 1, 5, 4, 2, 1, 10, 5, 4, 2, 1, 6, 3, 2, 1, 12, 6, 3, 2, 1, 7, 6, 3, 2, 1, 14, 7, 6, 3, 2, 1, 8, 4, 2, 1, 16, 8, 4, 2, 1, 9, 8, 4, 2, 1, 18, 9, 8, 4, 2, 1, 10, 5, 4, 2, 1, 20, 10, 5, 4, 2, 1, 11, 10, 5, 4, 2, 1, 22, 11, 10, 5, 4, 2, 1, 12, 6, 3
Offset: 2
Examples
Triangle begins: 1; 2,1; 2,1; 4,2,1; 3,2,1; 6,3,2,1; ... 7 -> 6 -> 3 -> 2 -> 1, so the 7th row is 6,3,2,1.
Crossrefs
A082404 is a better version.
Programs
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PARI
xnm1(n,p) = { print1(1" "); for(x=1,n, p1 = x; while(p1>1, if(p1%2==0,p1/=2,p1 = p1*p-1;); print1(p1" ") ) ) }
Extensions
Edited by N. J. A. Sloane, Dec 06 2008 at the suggestion of R. J. Mathar
Comments