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A250108
n*(n-1)/2 mod 2 + n*(n-1)/2 - n*( (n-1) mod 2 ).
0
0, 0, 4, 2, 10, 10, 22, 20, 36, 36, 56, 54, 78, 78, 106, 104, 136, 136, 172, 170, 210, 210, 254, 252, 300, 300, 352, 350, 406, 406, 466, 464, 528, 528, 596, 594, 666, 666, 742, 740, 820, 820, 904, 902, 990, 990, 1082, 1080, 1176, 1176, 1276, 1274, 1378
OFFSET
1,3
FORMULA
Empirical g.f.: -2*x^3*(x^3+2*x^2-x+2) / ((x-1)^3*(x+1)^2*(x^2+1)). - Colin Barker, Jun 06 2015
CROSSREFS
Sequence in context: A266851 A185732 A121794 * A210735 A075086 A284782
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 19 2014
STATUS
approved