id:A076982 - OEIS Search Results

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Number of triangular numbers that divide the n-th triangular number.

+0
4

1, 2, 3, 2, 3, 3, 2, 4, 4, 2, 4, 4, 2, 5, 6, 2, 3, 3, 3, 8, 4, 2, 4, 6, 2, 3, 5, 2, 4, 4, 2, 5, 3, 2, 10, 4, 2, 3, 7, 3, 4, 4, 2, 9, 5, 2, 4, 6, 2, 4, 5, 2, 3, 6, 5, 6, 3, 2, 6, 6, 2, 4, 7, 3, 5, 3, 2, 4, 6, 2, 5, 5, 2, 4, 7, 2, 6, 3, 3, 9, 3, 2, 5, 10, 2, 3, 5, 2, 5, 8, 3, 4, 3, 2, 8, 4, 2, 5, 10, 3, 3, 3 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Also number of oblong numbers that divide the n-th oblong number.`
	FORMULA	`a(n) = A007862(A000217(n)) = A129308(A002378(n)). - Ray Chandler (rayjchandler(AT)sbcglobal.net), Jun 21 2008`
	MAPLE	`a[1] := 1:for i from 1 to 200 do s := 0:for j from 1 to i do if((i(i+1)/2 mod j(j+1)/2)=0) then s := s+1:fi:od:a[i] := s:od:seq(a[l], l=1..200);`
	CROSSREFS	`Cf. A076983, A084260.` `Sequence in context: A030350 A026240 A124474 this_sequence A091935 A086063 A026263` `Adjacent sequences: A076979 A076980 A076981 this_sequence A076983 A076984 A076985`
	KEYWORD	`nonn`
	AUTHOR	`Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Oct 25 2002`
	EXTENSIONS	`More terms from Lior Manor (lior.manor(AT)gmail.com) Nov 06 2002` `More terms from Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Jan 26 2003`

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.

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