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 A145272 First differences of successive iterated triangular numbers. 1
 1, 3, 15, 210, 26565, 358999410, 64449908117864115 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Also a triangular number -- follows from the definition of A007501. LINKS 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: A003505 A270354 A120601 * A264705 A117820 A126453 Adjacent sequences:  A145269 A145270 A145271 * A145273 A145274 A145275 KEYWORD easy,nonn AUTHOR Greg Huber, Oct 06 2008 STATUS approved

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Last modified August 12 21:52 EDT 2022. Contains 356077 sequences. (Running on oeis4.)