id:A115017 - OEIS Search Results

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a(n) = largest triangular number dividing n.

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1, 1, 3, 1, 1, 6, 1, 1, 3, 10, 1, 6, 1, 1, 15, 1, 1, 6, 1, 10, 21, 1, 1, 6, 1, 1, 3, 28, 1, 15, 1, 1, 3, 1, 1, 36, 1, 1, 3, 10, 1, 21, 1, 1, 45, 1, 1, 6, 1, 10, 3, 1, 1, 6, 55, 28, 3, 1, 1, 15, 1, 1, 21, 1, 1, 66, 1, 1, 3, 10, 1, 36, 1, 1, 15, 1, 1, 78, 1, 10, 3, 1, 1, 28, 1, 1, 3, 1, 1, 45, 91, 1, 3, 1 (list; graph; listen)

	OFFSET	`1,3`
	FORMULA	`a(n) = A083312(n) *(A083312(n) +1)/2.`
	EXAMPLE	`a(12)=6 because the triangular numbers dividing 12 are 1,3, and 6.`
	MAPLE	`a:=proc(n) local P, j; P:={}: for j from 1 to n do if type(n/(j(j+1)/2), integer)=true then P:=P union {j(j+1)/2} else P:=P: fi od: P[nops(P)]; end: seq(a(n), n=1..105); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 01 2006`
	CROSSREFS	`Cf. A000217, A083312.` `Sequence in context: A123162 A083075 A069972 this_sequence A088439 A109446 A088441` `Adjacent sequences: A115014 A115015 A115016 this_sequence A115018 A115019 A115020`
	KEYWORD	`nonn`
	AUTHOR	`Leroy Quet (qq-quet(AT)mindspring.com), Feb 23 2006`
	EXTENSIONS	`More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 01 2006`

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Last modified November 18 20:14 EST 2008. Contains 147244 sequences.

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