A308897 Walk a rook along the square spiral numbered 1, 2, 3, ... (cf. A274640); a(n) = mex of earlier values the rook can move to.

1, 2, 1, 2, 3, 4, 1, 3, 4, 2, 3, 4, 1, 3, 4, 2, 5, 6, 7, 8, 1, 5, 6, 7, 8, 2, 5, 6, 7, 8, 1, 5, 6, 7, 8, 2, 3, 6, 5, 8, 7, 4, 1, 3, 6, 5, 8, 7, 4, 2, 3, 6, 5, 8, 7, 4, 1, 3, 6, 5, 8, 7, 4, 2, 9, 10, 11, 12, 13, 14, 15, 16, 1, 9, 10, 11, 12, 13, 14, 15, 16, 2

Offset: 1

Author

N. J. A. Sloane, Jul 02 2019

Keywords

• nonn

Comments

Mex here means "smallest positive missing number".

Add 1 to the terms of A308896.

Crossrefs

Cf. A274640, A308896.

Extensions

More terms from Rémy Sigrist, Jul 02 2019