A176867 Least odd number that requires n Collatz (3x+1) iterations to reach 1, or zero if there is no such number.

1, 0, 0, 0, 0, 5, 0, 3, 0, 13, 0, 53, 17, 35, 11, 23, 7, 15, 29, 9, 19, 37, 77, 25, 49, 99, 33, 65, 131, 43, 87, 173, 57, 115, 39, 79, 153, 305, 105, 203, 407, 135, 271, 541, 185, 361, 123, 247, 481, 169, 329, 641, 219, 427, 159, 295, 569, 1139, 379, 759, 283, 505, 1011

Offset

0,6

Comments

Both the 3x+1 steps and the halving steps are counted. a(n)=0 only for n = 1, 2, 3, 4, 6, 8, and 10. Sequence A033491 gives the least even or odd number requiring n iterations.

Links

T. D. Noe, Table of n, a(n) for n=0..1924

Crossrefs

Cf. A176866, A176868

Sequence in context: A355068 A261219 A085850 * A351208 A229175 A372836

Adjacent sequences: A176864 A176865 A176866 * A176868 A176869 A176870

Keyword

nonn

Author

T. D. Noe, Apr 27 2010

Status

approved