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A050542
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Iterated triangular numbers.
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1
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OFFSET
| 0,1
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FORMULA
| a(n)=binomial(a(n-1)+1, 2), a(0)=5
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MATHEMATICA
| a=5; lst={a}; Do[b=(a+1)*a/2; AppendTo[lst, b]; a=b, {n, 1, 9}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Mar 16 2010]
NestList[Binomial[#+1, 2]&, 5, 9] (* From Harvey P. Dale, Sep 24 2011 *)
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CROSSREFS
| A000217, A007501, A013589.
Sequence in context: A088418 A080490 A173736 * A091096 A116957 A124209
Adjacent sequences: A050539 A050540 A050541 * A050543 A050544 A050545
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KEYWORD
| easy,nice,nonn
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AUTHOR
| Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Dec 29 1999
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