A124925 - OEIS

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A124925

Interlaced triples: a(3n+1)=1. a(3n+2) = 2n+3. a(3n+3)= A028387(n).

1, 3, 1, 1, 5, 5, 1, 7, 11, 1, 9, 19, 1, 11, 29, 1, 13, 41, 1, 15, 55, 1, 17, 71, 1, 19, 89, 1, 21, 109, 1, 23, 131, 1, 25, 155, 1, 27, 181, 1, 29, 209, 1, 31, 239, 1, 33, 271, 1, 35, 305, 1, 37, 341, 1, 39, 379, 1, 41, 419, 1, 43, 461, 1, 45, 505, 1, 47, 551, 1, 49, 599, 1, 51, 649, 1, 53 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Three consecutive terms of the sequence define a polynomial a(3n+1)x^2 - a(3n+2)x +a(3n+3) which has a root x= 1 +n + golden ratio.`
	FORMULA	`a(n)= 3a(n-3) -3a(n-6) +a(n-9).` `G.f.: x(-1-3x-x^2+2x^3+4x^4-2x^5-x^6-x^7+x^8) / ((x-1)^3 (1+x+x^2)^3 ).`
	CROSSREFS	`Cf. A001622.` `Sequence in context: A108553 A176700 A158418 * A073145 A145033 A202672` `Adjacent sequences: A124922 A124923 A124924 * A124926 A124927 A124928`
	KEYWORD	`nonn,easy,less`
	AUTHOR	`Gary W. Adamson (qntmpkt(AT)yahoo.com), Nov 12 2006`
	EXTENSIONS	`Edited and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 28 2010`

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Last modified February 16 23:45 EST 2012. Contains 205978 sequences.