id:A113422 - OEIS Search Results

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a(n)=[(5n^2+1)/3].

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0, 2, 7, 15, 27, 42, 60, 82, 107, 135, 167, 202, 240, 282, 327, 375, 427, 482, 540, 602, 667, 735, 807, 882, 960, 1042, 1127, 1215, 1307, 1402, 1500, 1602, 1707, 1815, 1927, 2042, 2160, 2282, 2407, 2535, 2667, 2802, 2940, 3082, 3227, 3375, 3527, 3682, 3840 (list; graph; listen)

	OFFSET	`0,2`
	COMMENT	`If n<a(m) then all integer solutions (i,j,k) of 2i^2+2j^2+3k^2-2i*k=n satisfy max(\|i\|,\|j\|,\|k\|)<m.`
	FORMULA	`G.f.: (2x+3x^2+3x^3+2x^4)/((1-x)^2(1-x^3)). a(-n)=a(n). a(3n)=15n^2, a(3n+1)=15n^2+10n+2.`
	PROGRAM	`(PARI) a(n)=(5*n^2+1)\3`
	CROSSREFS	`Sequence in context: A167543 A029888 A005449 this_sequence A061802 A003452 A000148` `Adjacent sequences: A113419 A113420 A113421 this_sequence A113423 A113424 A113425`
	KEYWORD	`nonn`
	AUTHOR	`Michael Somos, Oct 31 2005`

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Last modified December 15 00:47 EST 2009. Contains 170825 sequences.

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