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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..70.

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

Cf. A127142, A127143.

Sequence in context: A019462 A078071 A084138 * A272668 A014406 A154426

Adjacent sequences:  A127138 A127139 A127140 * A127142 A127143 A127144

KEYWORD

nonn

AUTHOR

Bryan Jacobs (bryanjj(AT)gmail.com), Jan 06 2007

STATUS

approved

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Last modified February 26 04:23 EST 2020. Contains 332275 sequences. (Running on oeis4.)