login
A127141
Number of iterations needed before a previous value is reached in the Collatz variation: x_{i+1} = 3x_i+(2n+1) if x_i is odd or x_i/2 if x_i is even, with x_0 = 1.
2
3, 4, 4, 7, 7, 8, 5, 18, 9, 32, 11, 77, 25, 10, 6, 36, 29, 18, 17, 12, 28, 14, 23, 45, 73, 55, 91, 16, 17, 39, 7, 36, 40, 114, 87, 100, 93, 34, 54, 64, 15, 55, 171, 80, 57, 72, 42, 108, 24, 12, 97, 68, 31, 159, 88, 10, 41, 50, 23, 117, 63, 61, 8, 55, 72, 45, 68, 24, 18, 211, 57
OFFSET
0,1
EXAMPLE
a(1) = 4 because there are 4 steps to reach a previous value:
step 1: x = 3*1 +(2n+1) = 6
step 2: x = 6/2 = 3;
step 3: x = 3*3 +(2n+1) = 12
step 4: x = 12/2 = 6, which was the result of step 1
CROSSREFS
Sequence in context: A078071 A359789 A084138 * A272668 A014406 A154426
KEYWORD
nonn
AUTHOR
Bryan Jacobs (bryanjj(AT)gmail.com), Jan 06 2007
STATUS
approved