A332452 Starting from sigma(n), number of halving steps to reach 1 in '3x+1' problem, or -1 if this never happens.

0, 5, 2, 11, 6, 7, 3, 12, 7, 14, 7, 13, 12, 8, 8, 67, 14, 23, 6, 7, 5, 15, 8, 14, 67, 7, 7, 14, 13, 16, 5, 68, 9, 71, 9, 59, 15, 14, 14, 13, 7, 10, 12, 8, 24, 16, 9, 69, 22, 13, 16, 18, 71, 15, 16, 15, 8, 13, 14, 9, 68, 10, 10, 31, 8, 17, 11, 69, 10, 17, 16, 76, 16, 23, 69, 12, 10, 9, 8, 14, 61, 69, 8, 16, 72, 20, 15, 14, 13, 16, 15, 9, 7, 17

Offset

1,2

Links

Antti Karttunen, Table of n, a(n) for n = 1..8192

Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537

Index entries for sequences related to 3x+1 (or Collatz) problem

Index entries for sequences related to sigma(n)

Formula

a(n) = A006666(A000203(n)).

a(n) = A332209(n) - A332453(n).

Prog

(PARI)
A006666(n) = { my(t); while(n>1, if(n%2, n=3*n+1, n>>=1; t++)); (t); }; \\ From A006666
A332452(n) = A006666(sigma(n));

Crossrefs

Cf. A000203, A006666, A332209, A332453, A332454.

Sequence in context: A074642 A194034 A163257 * A176624 A131784 A302773

Adjacent sequences: A332449 A332450 A332451 * A332453 A332454 A332455

Keyword

nonn

Author

Antti Karttunen, Feb 16 2020

Status

approved