id:A056109 - OEIS Search Results

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Fifth spoke of a hexagonal spiral.

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1, 6, 17, 34, 57, 86, 121, 162, 209, 262, 321, 386, 457, 534, 617, 706, 801, 902, 1009, 1122, 1241, 1366, 1497, 1634, 1777, 1926, 2081, 2242, 2409, 2582, 2761, 2946, 3137, 3334, 3537, 3746, 3961, 4182, 4409, 4642, 4881, 5126, 5377, 5634, 5897, 6166, 6441 (list; graph; listen)

	OFFSET	`0,2`
	LINKS	`Tanya Khovanova, Recursive Sequences` `H. Bottomley, Illustration of initial terms` `G. Nebe and N. J. A. Sloane, Home page for hexagonal (or triangular) lattice A2`
	FORMULA	`a(n) = 3n^2+2n+1 = a(n-1)+6n-1 = 2a(n-1)-a(n-2)+6 = 3a(n-1)-3a(n-2)+a(n-3) = A056105(n)+4n = A056106(n)+3n = A056107(n)+2n = A056108(n)+n = A003215(n)-n`
	PROGRAM	`(PARI) a(n)=3n^2+2n+1 /* Michael Somos Aug 03 2006 */`
	CROSSREFS	`Cf. A054552 for example of square (or octagonal) spiral spoke.` `A008810(3n+1)=A056105(-n)=a(n). - Michael Somos Aug 03 2006.` `Sequence in context: A130051 A038795 A066486 this_sequence A023545 A038633 A083045` `Adjacent sequences: A056106 A056107 A056108 this_sequence A056110 A056111 A056112`
	KEYWORD	`easy,nonn`
	AUTHOR	`Henry Bottomley (se16(AT)btinternet.com), Jun 09 2000`

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Last modified September 6 16:04 EDT 2008. Contains 143483 sequences.

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