A287421 Positions of 2 in A287418.

3, 5, 9, 11, 15, 18, 20, 24, 27, 29, 33, 36, 38, 42, 45, 48, 50, 54, 56, 60, 63, 66, 68, 72, 74, 78, 81, 83, 87, 90, 92, 96, 99, 102, 104, 108, 110, 114, 117, 120, 122, 126, 128, 132, 135, 138, 140, 144, 146, 150, 153, 155, 159, 162, 164, 168, 171, 173, 177

Offset: 1

Author

Clark Kimberling, May 26 2017

Keywords

• nonn
• easy

Comments

a(n) - a(n-1) is in {2,3,4} for n >= 1; also, 3n - a(n) is in {0, 1} for n >= 1. The first 20 numbers 3n - a(n) are 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, with 1 in positions given by A287420.

Links

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

Crossrefs

Cf. A287418, A287419, A287421.

Programs

Mathematica

s = Nest[Flatten[# /. {0->{0, 1, 2}, 1->{1, 2, 0}, 2->{1, 0, 2}}] &, {0}, 9]; (*A287418*)
Flatten[Position[s, 0]]; (*A287419*)
Flatten[Position[s, 1]]; (*A287420*)
Flatten[Position[s, 2]]; (*A287421*)