A347272 Main diagonal of the square array A347270.

1, 1, 5, 4, 2, 8, 26, 4, 52, 1, 16, 2, 1, 16, 8, 2, 4, 8, 4, 1, 4, 1, 4, 4, 4, 1, 155, 1, 4, 2, 395, 2, 1, 2, 1, 2, 1, 4, 4, 4, 668, 1, 4, 1, 4, 2, 425, 1, 1, 4, 2, 4, 2, 850, 425, 1, 1, 2, 2, 4, 2, 4858, 2429, 1, 4, 2, 1, 2, 1, 4, 2308, 4, 3644, 1, 1, 2, 1, 1, 4, 4, 4

Offset

0,3

Comments

A347270 is related to the 3x + 1 (or Collatz) problem.

Conjectures from Alois P. Heinz, Aug 31 2021: (Start)

a(n) in {1, 2, 4, 5, 8, 10, 16, 26, 52, 53, 106, 155, 395, 425, 488, 668, 850, 866, 1732, 2308, 2429, 3644, 4858} for n >= 0.

a(n) in {1, 2, 4} for n >= 110. (End)

Links

Alois P. Heinz, Table of n, a(n) for n = 0..10000

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

Maple

b:= proc(n, k) option remember; `if`(k=0, n, (j->
      `if`(j::even, j/2, 3*j+1))(b(n, k-1)))
    end:
a:= n-> b(n+1, n):
seq(a(n), n=0..80);  # Alois P. Heinz, Aug 25 2021

Mathematica

b[n_, k_] := b[n, k] = If[k == 0, n, Function[j,
     If[EvenQ[j], j/2, 3*j + 1]][b[n, k - 1]]];
a[n_] := b[n + 1, n];
Table[a[n], {n, 0, 80}] (* Jean-François Alcover, Apr 07 2022, after Alois P. Heinz *)

Crossrefs

Cf. A006370, A033478, A033479, A075884, A076536, A153727, A347270, A371690 (parity).

Sequence in context: A222307 A368274 A175838 * A097960 A019712 A020799

Adjacent sequences: A347269 A347270 A347271 * A347273 A347274 A347275

Keyword

nonn

Author

Omar E. Pol, Aug 25 2021

Status

approved