id:A051938 - OEIS Search Results

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A051938

Truncated triangular numbers: a(n)=n*(n+1)/2-18.

+0
1

3, 10, 18, 27, 37, 48, 60, 73, 87, 102, 118, 135, 153, 172, 192, 213, 235, 258, 282, 307, 333, 360, 388, 417, 447, 478, 510, 543, 577, 612, 648, 685, 723, 762, 802, 843, 885, 928, 972, 1017, 1063, 1110, 1158, 1207, 1257, 1308, 1360, 1413, 1467, 1522, 1578 (list; graph; listen)

	OFFSET	`6,1`
	COMMENT	`If a 3-set Y and a 3-set Z, having one element in common, are subsets of an n-set X then a(n+2) is the number of 3-subests of X intersecting both Y and Z. - Milan R. Janjic (agnus(AT)blic.net), Oct 03 2007`
	LINKS	`Milan Janjic, Two Enumerative Functions`
	CROSSREFS	`a(n)=A000217(n)-18, n>5` `Sequence in context: A063211 A063111 A031063 this_sequence A074893 A074178 A127852` `Adjacent sequences: A051935 A051936 A051937 this_sequence A051939 A051940 A051941`
	KEYWORD	`easy,nice,nonn`
	AUTHOR	`Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Dec 21 1999`

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Last modified September 7 15:23 EDT 2008. Contains 143483 sequences.

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