A212439 a(n) = 2*n + A181935(n) mod 2.

1, 3, 5, 6, 8, 11, 13, 15, 17, 19, 20, 22, 24, 27, 29, 30, 32, 35, 37, 38, 40, 42, 45, 47, 49, 51, 52, 54, 56, 59, 61, 63, 65, 67, 69, 70, 72, 74, 77, 79, 81, 83, 85, 86, 88, 90, 93, 94, 96, 99, 101, 102, 104, 106, 108, 111, 113, 115, 116, 118, 120, 123, 125

Offset: 0

Author

Reinhard Zumkeller, May 17 2012

Keywords

• nonn
• base

Comments

A212444 gives iterations starting from 0.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..8191
• Benjamin Chaffin, John P. Linderman, N. J. A. Sloane, and Allan R. Wilks, On Curling Numbers of Integer Sequences, Journal of Integer Sequences, Vol. 16 (2013), Article 13.4.3.
• Index entries for sequences related to binary expansion of n.

Crossrefs

Cf. A014601, A007088, A181935, A212412, A212444.

Programs

Haskell

a212439 n = 2 * n + a212412 n

Mathematica

f[n_, e_] := Module[{d = IntegerDigits[n, 2^e]}, Length[Split[d][[-1]]] - If[SameQ @@ d && Mod[n, 2^e] < 2^(e - 1), 1, 0]]; a[n_] := 2*n + Mod[Max[Table[f[n, e], {e, Range[Max[1, Floor[Log2[n]]]]}]], 2]; a[0] = 1; Array[a, 100, 0] (* Amiram Eldar, Apr 08 2025 *)

Formula

a(n) = 2*n + A212412(n): concatenation of binary representation of n and the parity of its curling number.