id:A128424 - OEIS Search Results

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a(n)=floor[sqrt[a(n-1)^2+a(n-2)^2+a(n-1)*a(n-2)]], a(1)=1, a(2)=3.

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1, 3, 3, 5, 7, 10, 14, 20, 29, 42, 61, 89, 130, 190, 278, 407, 596, 873, 1279, 1874, 2746, 4024, 5897, 8642, 12665, 18561, 27202, 39866, 58426, 85627, 125492, 183917, 269543, 395034, 578950, 848492, 1243525, 1822474, 2670965, 3914489, 5736962 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`For triangle with sides a(n-1), a(n-2) and angle 120 deg between them, a(n) = (floor of value of) the third side.`
	MATHEMATICA	`a[1]=1; a[2]=3; a[n_]:=a[n]=Floor[Sqrt[a[n-1]^2+a[n-2]^2+a[n-1]*a[n-2]]] Table[a[n], {n, 45}]`
	CROSSREFS	`Cf. A104803, A104804, A104805.` `Sequence in context: A076524 A050824 A086341 this_sequence A129758 A001588 A107029` `Adjacent sequences: A128421 A128422 A128423 this_sequence A128425 A128426 A128427`
	KEYWORD	`nonn`
	AUTHOR	`Zak Seidov (zakseidov(AT)yahoo.com), May 04 2007`

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Last modified July 23 17:35 EDT 2008. Contains 142285 sequences.

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