id:A128223 - OEIS Search Results

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a(n) = if n mod 2 = 0 then n*(n+1)/2 otherwise (n+1)^2/2-1.

+0
3

0, 1, 3, 7, 10, 17, 21, 31, 36, 49, 55, 71, 78, 97, 105, 127, 136, 161, 171, 199, 210, 241, 253, 287, 300, 337, 351, 391, 406, 449, 465, 511, 528, 577, 595, 647, 666, 721, 741, 799, 820, 881, 903, 967, 990, 1057, 1081, 1151, 1176, 1249, 1275, 1351, 1378, 1457, 1485 (list; graph; listen)

	OFFSET	`0,3`
	COMMENT	`a(n-1) is the length of the shortest path along the edges of the complete graph with n vertices. - Martin Fuller, Dec 06 2007`
	EXAMPLE	`a(5) = 17 = (5 + 1 + 5 + 1 + 5), row 5 of A128222.`
	MAPLE	`f:=n-> if n mod 2 = 0 then n*(n+1)/2 else (n+1)^2/2-1; fi;`
	CROSSREFS	`Row sums of A128222.` `Cf. A024206, row sums of A128221 = A128174 * A127701.` `Cf. A128221, A024206, A127701, A128174.` `Sequence in context: A114113 A100056 A163714 this_sequence A111244 A022120 A041191` `Adjacent sequences: A128220 A128221 A128222 this_sequence A128224 A128225 A128226`
	KEYWORD	`nonn`
	AUTHOR	`Gary W. Adamson (qntmpkt(AT)yahoo.com), Feb 19 2007`
	EXTENSIONS	`Edited by N. J. A. Sloane (njas(AT)research.att.com), Dec 06 2007`

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Last modified November 27 14:50 EST 2009. Contains 167570 sequences.

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