A287420 Positions of 1 in A287418.

2, 4, 7, 10, 13, 17, 19, 23, 25, 28, 31, 35, 37, 41, 43, 47, 49, 52, 55, 58, 62, 65, 67, 70, 73, 77, 79, 82, 85, 89, 91, 95, 97, 101, 103, 106, 109, 112, 116, 119, 121, 124, 127, 131, 133, 137, 139, 142, 145, 148, 152, 154, 158, 160, 163, 166, 170, 172, 176

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 {1, 2} for n >= 1. The first 20 numbers 3n - a(n) are 1, 2, 2, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 2, 2, 2, with 1 in positions given by A287419.

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*)