A390595 Numbers k such that the binary length of k is the same as the binary length of 3*k+1 reduced by the largest possible power of two.

1, 19, 25, 35, 39, 49, 57, 67, 71, 75, 79, 83, 89, 97, 105, 113, 121, 131, 135, 139, 143, 147, 151, 155, 159, 163, 167, 177, 185, 193, 201, 209, 217, 225, 233, 241, 249, 259, 263, 267, 271, 275, 279, 283, 287, 291, 295, 299, 303, 307, 311, 315, 319, 323, 327, 331

Offset

1,2

Links

Hugo Pfoertner, Table of n, a(n) for n = 1..10000

Mathematica

A390595Q[k_] := BitLength[k] == BitLength[#/2^IntegerExponent[#, 2]] & [3*k + 1];
Select[Range[500], A390595Q] (* Paolo Xausa, Nov 22 2025 *)

Prog

(PARI) is_a390595(k) = my(m=3*k+1); #binary(k) == #binary(m>>valuation(m, 2))

Crossrefs

Cf. A067745, A070939, A075677.

Positions of zeros in A390768.

Sequence in context: A061841 A219957 A276437 * A129071 A066125 A181691

Adjacent sequences: A390592 A390593 A390594 * A390596 A390597 A390598

Keyword

nonn

Author

Hugo Pfoertner, Nov 21 2025

Status

approved