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A242983
n/2 * (n^3 - 2*n^2 - 2*n + 5).
0
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
0,4
COMMENTS
For n>1, number of ways to place two dominoes horizontally on an n X n chessboard.
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.
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 *)
CROSSREFS
Sequence in context: A072259 A272233 A283164 * A167533 A244907 A374963
KEYWORD
nonn,easy
AUTHOR
Ralf Stephan, Jun 09 2014
STATUS
approved