A287565 Positions of 3 in A287561.

4, 6, 11, 13, 19, 21, 28, 30, 34, 39, 41, 48, 49, 56, 58, 63, 66, 71, 73, 80, 81, 88, 90, 95, 100, 102, 107, 109, 115, 117, 124, 126, 131, 133, 140, 142, 146, 151, 153, 160, 161, 168, 170, 175, 180, 182, 187, 189, 193, 200, 202, 207, 212, 214, 219, 221, 227

Offset: 1

Author

Clark Kimberling, May 31 2017

Keywords

• nonn
• easy

Comments

a(n) - a(n-1) is in {1,2,3,4,5,6,7} for n >= 1; also, 4n - a(n) is in {0,1,2,3} for n >= 1. The first 20 numbers 4n - a(n) are 0, 2, 1, 3, 1, 3, 0, 2, 2, 1, 3, 0, 3, 0, 2, 1, 2, 1, 3, 0, with

0 in positions given by A287562,

1 in positions given by A287563,

2 in positions given by A287564,

3 in positions given by A287565.

Links

• Clark Kimberling, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A287561, A287562, A287563, A287565.

Programs

Mathematica

s = Nest[Flatten[# /. {0 -> {0, 2, 1, 3}, 1 -> {2, 1, 3, 0}, 2 -> {1, 3, 0, 2}, 3 -> {3, 0, 2, 1}}] &, {0}, 9];   (* A287561 *)
Flatten[Position[s, 0]]; (* A287562 *)
Flatten[Position[s, 1]]; (* A287563 *)
Flatten[Position[s, 2]]; (* A287564 *)
Flatten[Position[s, 3]]; (* A287565 *)

Formula

a(n) = 4n - A287561(n) for n >= 1.