A081661 - OEIS

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A081661

Partial sums of A081660.

1, 3, 8, 16, 31, 57, 106, 198, 377, 727, 1420, 2796, 5539, 11013, 21950, 43810, 87517, 174915, 349696, 699240, 1398311, 2796433, 5592658, 11185086, 22369921, 44739567, 89478836, 178957348, 357914347, 715828317, 1431656230, 2863312026 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,2`
	FORMULA	`a(n)=2^(n+2)/3+(n^2+n-1)/2+(-1)^n/6`
	CROSSREFS	`Cf. A001045.` `Sequence in context: A002624 A068039 A188123 * A005103 A001978 A173283` `Adjacent sequences: A081658 A081659 A081660 * A081662 A081663 A081664`
	KEYWORD	`easy,nonn`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Mar 26 2003`

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Last modified February 15 18:22 EST 2012. Contains 205835 sequences.