A145272 - OEIS

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A145272

First differences of successive iterated triangular numbers.

1, 3, 15, 210, 26565, 358999410, 64449908117864115 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also a triangular number -- follows from the definition of A007501.`
	FORMULA	`a(n)=T(x(n-1))-x(n-1) where x(n)=T(x(n-1)) and T(x)=x*(x+1)/2.`
	EXAMPLE	`a(1)=T(2)-2` `a(2)=T(3)-3` `a(3)=T(6)-6`
	CROSSREFS	`A007501: First differences of successive terms of sequence A007501.` `Sequence in context: A195515 A003505 A120601 * A117820 A126453 A007081` `Adjacent sequences: A145269 A145270 A145271 * A145273 A145274 A145275`
	KEYWORD	`easy,nonn`
	AUTHOR	`Greg Huber (huber(AT)alum.mit.edu), Oct 06 2008`

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Last modified February 16 21:51 EST 2012. Contains 205978 sequences.