

A261870


a(n) = minimal number of steps to get from n to 1, where a step is x > 3x1 if x is odd, or x > either x/2 or 3x1 if x is even.


2



0, 1, 4, 2, 15, 5, 13, 3, 16, 11, 6, 6, 19, 14, 9, 4, 35, 17, 17, 12, 25, 7, 20, 7, 33, 15, 15, 15, 10, 10, 23, 5, 36, 36, 18, 18, 31, 18, 13, 13, 26, 26, 8, 8, 26, 21, 21, 8, 34, 34, 21, 16, 16, 16, 29, 16, 29, 11, 11, 11, 24, 24, 24, 6, 37, 37, 24, 19, 19, 19, 19, 19, 32, 32, 19, 19, 14, 14, 14, 14, 27, 27, 27, 27, 27, 9, 40, 9, 27, 27, 22, 22, 22, 22, 22, 9, 35, 35, 35, 22
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OFFSET

1,3


COMMENTS

The 3x1 variation of Collatz conjecture would imply that this sequence is well defined. In turn, if this sequence is welldefined, then A109732 represents a permutation of the odd positive integers.


LINKS

Max Alekseyev, Table of n, a(n) for n = 1..1000


PROG

(PARI) { A261870(n) = my(S, k); S=[n]; k=0; while( S[1]!=1, k++; S=vecsort( concat(apply(x>3*x1, S), apply(x>x\2, select(x>x%2==0, S) )), , 8); ); k } /* Max Alekseyev, Sep 03 2015 */


CROSSREFS

Cf. A127885, A006577, A109732.
Sequence in context: A019012 A154333 A185130 * A325516 A299789 A121662
Adjacent sequences: A261867 A261868 A261869 * A261871 A261872 A261873


KEYWORD

nonn


AUTHOR

Max Alekseyev, Sep 03 2015


STATUS

approved



