id:A104581 - OEIS Search Results

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Expansion of 1/(1+x+x^3+x^4).

+0
1

1, -1, 1, -2, 2, -2, 3, -3, 3, -4, 4, -4, 5, -5, 5, -6, 6, -6, 7, -7, 7, -8, 8, -8, 9, -9, 9, -10, 10, -10, 11, -11, 11, -12, 12, -12, 13, -13, 13, -14, 14, -14, 15, -15, 15, -16, 16, -16, 17, -17, 17, -18, 18, -18, 19, -19, 19, -20, 20, -20, 21, -21, 21, -22, 22, -22, 23, -23, 23, -24, 24, -24, 25, -25, 25, -26, 26, -26 (list; graph; listen)

	OFFSET	`0,4`
	COMMENT	`Diagonal sums of Riordan array (1/(1+x+x^2+x^3+x^4),x/(1+x+x^2+x^3+x^4)). Convolution of (n+1)(-1)^n and A010892.`
	FORMULA	`a(n)=floor((n+3)/3)(-1)^n; a(n)=sum{k=0..n, (n-k+1)(-1)^(n-k)2sin(pik/3+pi/3)/sqrt(3)}.`
	MATHEMATICA	`CoefficientList[ Series[1/(1 + x + x^3 + x^4), {x, 0, 80}], x] (from Robert G. Wilson v Mar 24 2005)`
	CROSSREFS	`Cf. A008620.` `Sequence in context: A086161 A002264 A008620 this_sequence A113675 A020912 A099199` `Adjacent sequences: A104578 A104579 A104580 this_sequence A104582 A104583 A104584`
	KEYWORD	`easy,sign`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Mar 16 2005`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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