A225773 The squares on a chessboard that are black, counting from top left corner and down.

2, 4, 6, 8, 9, 11, 13, 15, 18, 20, 22, 24, 25, 27, 29, 31, 34, 36, 38, 40, 41, 43, 45, 47, 50, 52, 54, 56, 57, 59, 61, 63

Offset

1,1

Comments

Equivalently it represents the squares that are white, counting from bottom left corner and up.

Links

Table of n, a(n) for n=1..32.

Formula

a(1) = 2

a(n) = a(n-1) + 2 + (mod(a(n-1)+1, 8) == 0) - (mod(a(n-1), 8) == 0)

Mathematica

sqColor[n_] := Mod[n, 2] + (1 - 2*Mod[n, 2])*Mod[Floor[(n - 1)/8], 2]; Select[Range[64], sqColor[#] == 0 &]

Crossrefs

Cf. A225240 (white-squares sequence).

Sequence in context: A228246 A184587 A345436 * A233671 A348854 A143346

Adjacent sequences: A225770 A225771 A225772 * A225774 A225775 A225776

Keyword

nonn,easy,fini,full

Author

Jonas Hallgren, Jul 26 2013

Status

approved