id:A116413 - OEIS Search Results

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Expansion of (1+x)/(1-2x-x^2-x^3).

+0
2

1, 3, 7, 18, 46, 117, 298, 759, 1933, 4923, 12538, 31932, 81325, 207120, 527497, 1343439, 3421495, 8713926, 22192786, 56520993, 143948698, 366611175, 933692041, 2377943955, 6056191126, 15424018248, 39282171577, 100044552528 (list; graph; listen)

	OFFSET	`0,2`
	COMMENT	`Diagonal sums of number triangle A116412. A078058 is an alternating sign version.`
	FORMULA	`a(n)=2a(n-1)+a(n-2)+a(n-3); a(n)=sum{k=0..floor(n/2), sum{j=0..n-k, C(k+1,j)C(n-k-j,k)2^(n-2k-j)}}.`
	CROSSREFS	`Sequence in context: A000226 A036883 A114713 this_sequence A078058 A052960 A059512` `Adjacent sequences: A116410 A116411 A116412 this_sequence A116414 A116415 A116416`
	KEYWORD	`easy,nonn`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Feb 13 2006`

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Last modified July 25 07:41 EDT 2008. Contains 142293 sequences.

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