id:A084099 - OEIS Search Results

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

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5

1, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0, 2, 0, -2, 0 (list; graph; listen)

	OFFSET	`0,2`
	COMMENT	`Inverse binomial transform of A077860. Partial sums of A084100.` `Transform of sqrt(1+2x)/sqrt(1-2x) (A063886) under the Chebyshev transformation A(x)->((1-x^2)/(1+x^2))A(x/(1+x^2)). - Paul Barry (pbarry(AT)wit.ie), Oct 12 2004`
	FORMULA	`Euler transform of length 4 sequence [ 2, -3, 0, 1]. - Michael Somos Aug 04 2009`
	EXAMPLE	`1 + 2x - 2x^3 + 2x^5 - 2x^7 + 2x^9 - 2x^11 + 2x^13 - 2x^15 + ...`
	PROGRAM	`(PARI) {a(n) = if( n<1, n==0, 2 * if(n%2, (-1)^(n\2)) )} /* Michael Somos Aug 04 2009 */`
	CROSSREFS	`2 * A101455(n) = a(n) unless n=0.` `Sequence in context: A101227 A021499 A010673 this_sequence A036665 A053472 A036664` `Adjacent sequences: A084096 A084097 A084098 this_sequence A084100 A084101 A084102`
	KEYWORD	`easy,sign`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), May 15 2003`

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Last modified December 13 23:45 EST 2009. Contains 170824 sequences.

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