A287400 Positions of 2 in A287397.

3, 4, 9, 12, 13, 18, 19, 24, 27, 28, 33, 36, 39, 40, 45, 48, 49, 54, 57, 58, 63, 66, 67, 72, 73, 78, 81, 84, 85, 90, 93, 94, 99, 100, 105, 108, 109, 114, 117, 120, 121, 126, 129, 130, 135, 138, 139, 144, 147, 148, 153, 154, 159, 162, 163, 168, 171, 174, 175

Offset: 1

Author

Clark Kimberling, May 25 2017

Keywords

• nonn
• easy

Comments

a(n) - a(n-1) is in {1,3,5} for n >= 1; also, 3n - a(n) is in {0, 2} for n >= 1. The first 20 numbers 3n - a(n) are 0, 2, 0, 0, 2, 0, 2, 0, 0, 2, 0, 0, 0, 2, 0, 0, 2, 0, 0, 2, with 2 in positions given by A287399.

Links

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

Crossrefs

Cf. A287397, A287398, A287399.

Programs

Mathematica

s = Nest[Flatten[# /. {0->{0, 1, 2}, 1->{2, 1, 0}, 2->{1, 0, 2}}] &, {0}, 9]; (*A287397*)
Flatten[Position[s, 0]]; (*A287398*)
Flatten[Position[s, 1]]; (*A287399*)
Flatten[Position[s, 2]]; (*A287400*)