A242983 n/2 * (n^3 - 2*n^2 - 2*n + 5).

0, 1, 1, 12, 58, 175, 411, 826, 1492, 2493, 3925, 5896, 8526, 11947, 16303, 21750, 28456, 36601, 46377, 57988, 71650, 87591, 106051, 127282, 151548, 179125, 210301, 245376, 284662, 328483, 377175, 431086, 490576, 556017

Offset: 0

Author

Ralf Stephan, Jun 09 2014

Keywords

• nonn
• easy

Comments

For n>1, number of ways to place two dominoes horizontally on an n X n chessboard.

Links

• Index entries for sequences related to dominoes
• Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).

Crossrefs

Cf. A242856, A242861.

Programs

Mathematica

Table[n/2 (n^3-2n^2-2n+5),{n,0,40}] (* or *) LinearRecurrence[{5,-10,10,-5,1},{0,1,1,12,58},40] (* Harvey P. Dale, Jul 19 2018 *)

Formula

a(n) = A019582(n) + A077414(n-2), n>1.

G.f.: x*(-2*x^3 + 17*x^2 - 4*x + 1) / (1-x)^5.