A199636 Irregular rows of odd numbers that produce n even numbers in their Collatz iteration.

5, 3, 21, 13, 85, 17, 53, 11, 35, 113, 341, 7, 23, 69, 75, 213, 227, 15, 45, 141, 151, 453, 1365, 9, 29, 93, 277, 301, 853, 909, 19, 61, 181, 201, 565, 605, 1813, 5461, 37, 117, 369, 373, 401, 403, 1109, 1137, 1205, 3413, 3637, 25, 77, 81, 241, 245, 267, 725

Offset

4,1

Comments

It is conjectured that every odd number greater than 1 eventually appears in this sequence. The smallest and largest terms in row n are A199637(n) and A199638(n). The number of terms in row n is A131450(n) for n > 3.

The 10th and 20th rows are A199817 and A199818.

Links

T. D. Noe, Rows n = 4..33, flattened

Example

Triangle begins:
   5;
   3;
  21;
  13;
  85;
  17, 53;
  11, 35, 113, 341;
   7, 23,  69,  75, 213, 227;
  ...

Mathematica

Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; nn = 16; t = Table[{}, {nn}]; Do[len = Length[Select[Collatz[n], EvenQ]]; If[0 < len <= nn, AppendTo[t[[len]], n]], {n, 1, 25000, 2}]; t

Crossrefs

Sequence in context: A099730 A072800 A199637 * A324038 A221473 A199638

Adjacent sequences: A199633 A199634 A199635 * A199637 A199638 A199639

Keyword

nonn,tabf

Author

T. D. Noe, Nov 14 2011

Status

approved