A108479 - OEIS

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A108479

Diagonal sums of number triangle A086645.

1, 1, 2, 7, 17, 44, 117, 305, 798, 2091, 5473, 14328, 37513, 98209, 257114, 673135, 1762289, 4613732, 12078909, 31622993, 82790070, 216747219, 567451585, 1485607536, 3889371025, 10182505537, 26658145586, 69791931223, 182717648081 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,3`
	FORMULA	`G.f.: (1-x-x^2)/(1-2x-x^2-2x^3+x^4); a(n)=2(n-1)+a(n-2)+2a(n-3)-a(n-4); a(n)=sum{k=0..floor(n/2), C(2(n-k), 2k)}; a(n)=sum{k=0..floor(n/2), sum{j=0..n-k, C(2(n-2k), j)C(2k, j)}}.`
	CROSSREFS	`Sequence in context: A175660 A175120 A106910 * A178441 A014742 A085411` `Adjacent sequences: A108476 A108477 A108478 * A108480 A108481 A108482`
	KEYWORD	`easy,nonn`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Jun 04 2005`

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Last modified February 17 19:13 EST 2012. Contains 206085 sequences.