A393187 a(n) = n XOR (2 * (n AND -n)) assuming a two's complement representation of negative values.

3, 6, 1, 12, 7, 2, 5, 24, 11, 14, 9, 4, 15, 10, 13, 48, 19, 22, 17, 28, 23, 18, 21, 8, 27, 30, 25, 20, 31, 26, 29, 96, 35, 38, 33, 44, 39, 34, 37, 56, 43, 46, 41, 36, 47, 42, 45, 16, 51, 54, 49, 60, 55, 50, 53, 40, 59, 62, 57, 52, 63, 58, 61, 192, 67, 70, 65

Offset

1,1

Comments

Computed by Wolfram's 2-state 2-symbol Turing machine 2223 when started with n on the tape.

Bitflip of the second lowest bit of the odd part of n. - Ruud H.G. van Tol, Apr 26 2026

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_] := BitXor[n, 2*BitAnd[n, -n]]; Array[a, 68] (* Michael De Vlieger, Feb 06 2026 *)

Prog

(PARI) a(n) = bitxor(n, 2*bitand(n, -n)); \\ Michel Marcus, Feb 05 2026
(PARI) a(n) = bitxor(n, 2<<valuation(n, 2)); \\ Ruud H.G. van Tol, Apr 26 2026
(Python)
def A393187(n): return n^((n&-n)<<1) # Chai Wah Wu, Feb 07 2026

Crossrefs

Cf. A000265, A006519, A393188, A392245.

Sequence in context: A026250 A210033 A209144 * A130724 A120229 A266151

Adjacent sequences: A393184 A393185 A393186 * A393188 A393189 A393190

Keyword

nonn,easy

Author

Sean A. Irvine, Feb 04 2026

Status

approved