A233137 Reversed shortest (x+1,2x)-code of n.

1, 2, 12, 22, 122, 212, 1212, 222, 1222, 2122, 12122, 2212, 12212, 21212, 121212, 2222, 12222, 21222, 121222, 22122, 122122, 212122, 1212122, 22212, 122212, 212212, 1212212, 221212, 1221212, 2121212, 12121212, 22222, 122222, 212222, 1212222, 221222, 1221222

Offset

1,2

Comments

(See A233135.)

Links

Clark Kimberling, Table of n, a(n) for n = 1..1000

Formula

Define h(x) = x - 1 if x is odd and h(x) = x/2 if x is even, and define H(x,1) = h(x) and H(x,k) = H(H(x,k-1)). For each n > 1, the sequence (H(n,k)) decreases to 1 through two kinds of steps; write 1 when the step is x - 1 and write 2 when the step is x/2. A233137(n) is the concatenation of 1s and 2s, as in the Mathematica program.

Mathematica

b[x_] := b[x] = If[OddQ[x], x - 1, x/2]; u[n_] := 2 - Mod[Drop[FixedPointList[b, n], -3], 2]; u[1] = {1}; t = Table[u[n], {n, 1, 30}]; Table[FromDigits[u[n]], {n, 1, 50}]  (* A233137 *)
Flatten[t]  (* A233138 *)
Table[FromDigits[Reverse[u[n]]], {n, 1, 30}]  (* A233135 *)
Flatten[Table[Reverse[u[n]], {n, 1, 30}]]  (* A233136 *)

Crossrefs

Cf. A040039, A135529, A232559, A000045, A233135, A233136, A233138.

Sequence in context: A108960 A111095 A073211 * A094626 A093378 A012664

Adjacent sequences: A233134 A233135 A233136 * A233138 A233139 A233140

Keyword

nonn,easy

Author

Clark Kimberling, Dec 05 2013

Status

approved