id:A074061 - OEIS Search Results

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Positive integers n such that 24*n^2-23 is a square.

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1, 4, 6, 39, 59, 386, 584, 3821, 5781, 37824, 57226, 374419, 566479, 3706366, 5607564, 36689241, 55509161, 363186044, 549484046, 3595171199, 5439331299, 35588525946, 53843828944, 352290088261, 532998958141, 3487312356664 (list; graph; listen)

	OFFSET	`0,2`
	LINKS	`Index entries for two-way infinite sequences` `K. S. Brown, Numbers Expressible as (a^2-1)(b^2-1)`
	FORMULA	`a(2n-1) = round((1/2)(1-(1/2)/sqrt(6))(sqrt(2)+sqrt(3))^(2n)); a(2n)=round(c*(sqrt(2)+sqrt(3))^(2n+1)) with c =0.191357750597... - Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 22 2002` `G.f.: (1-x)(1+5x+x^2)/(1-10x^2+x^4). a(n)=10a(n-2)-a(n-4)=a(-1-n).`
	PROGRAM	`(PARI) a(n)=if(n<0, a(-1-n), polcoeff((1-x)(1+5x+x^2)/(1-10x^2+x^4)+xO(x^n), n))`
	CROSSREFS	`Sequence in context: A092765 A056315 A103234 this_sequence A125081 A023644 A145387` `Adjacent sequences: A074058 A074059 A074060 this_sequence A074062 A074063 A074064`
	KEYWORD	`nonn`
	AUTHOR	`Michael Somos, Aug 19, 2002`

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Last modified December 10 00:48 EST 2009. Contains 170565 sequences.

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