A393188 a(n) = u(n) OR (u(n) - 1) where u(n) = n + (n AND -n) assuming a two's complement representation for negative values.

3, 7, 7, 15, 7, 15, 15, 31, 11, 15, 15, 31, 15, 31, 31, 63, 19, 23, 23, 31, 23, 31, 31, 63, 27, 31, 31, 63, 31, 63, 63, 127, 35, 39, 39, 47, 39, 47, 47, 63, 43, 47, 47, 63, 47, 63, 63, 127, 51, 55, 55, 63, 55, 63, 63, 127, 59, 63, 63, 127, 63, 127, 127, 255

Offset

1,1

Comments

Computed by Wolfram's 2-state 2-symbol Turing machine 2079 when started with n on the tape.

Links

Sean A. Irvine, Table of n, a(n) for n = 1..1000

Stephen Wolfram, P vs. NP and the Difficulty of Computation: A Ruliological Approach, 2026.

Mathematica

a[n_] := BitOr[#, # - 1] &[n + BitAnd[n, -n]]; Array[a, 64] (* Michael De Vlieger, Feb 06 2026 *)

Prog

(PARI) a(n) = my(u=n + bitand(n, -n)); bitor(u, u-1); \\ Michel Marcus, Feb 07 2026
(Python) def a(n): return n + (n & -n) | (n + (n & -n)) - 1 # Aitzaz Imtiaz, Feb 07 2026

Crossrefs

Cf. A006519, A393187, A392245.

Sequence in context: A118259 A060845 A386850 * A059478 A175329 A081218

Adjacent sequences: A393185 A393186 A393187 * A393189 A393190 A393191

Keyword

nonn,easy

Author

Sean A. Irvine, Feb 04 2026

Status

approved