A080828 Triangle read by rows in which n-th row gives trajectory of n (omitting n itself) under the map k -> 3k-1 if k odd, k -> k/2 if k even, stopping when reach 1, 5 or 17.

1, 8, 4, 2, 1, 2, 1, 14, 7, 20, 10, 5, 3, 8, 4, 2, 1, 20, 10, 5, 4, 2, 1, 26, 13, 38, 19, 56, 28, 14, 7, 20, 10, 5, 5, 32, 16, 8, 4, 2, 1, 6, 3, 8, 4, 2, 1, 38, 19, 56, 28, 14, 7, 20, 10, 5, 7, 20, 10, 5, 44, 22, 11, 32, 16, 8, 4, 2, 1, 8, 4, 2, 1, 50, 25, 74, 37, 110, 55, 164, 82, 41, 122

Offset: 2

Author

Cino Hilliard, Mar 27 2003

Keywords

• easy
• nonn
• tabf

Comments

The 3x-1 problem terminates at 4,2,1 or 20,10,5 or 68,34,17. The x-1 problem terminates at 4,2,1 or 3,2,1.

Examples

			5->14->7->20->10->5 so 5th row is 14,7,20,10,5.
		

Programs

PARI

x3nm1(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" "); if(p1 == 5 || p1 == 17,break); ) ) }