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Search: id:A061213
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| A061213 |
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a(n) = product of first n triangular numbers (A000217) + 1. |
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+0
1
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| 2, 4, 19, 181, 2701, 56701, 1587601, 57153601, 2571912001, 141455160001, 9336040560001, 728211163680001, 66267215894880001, 6958057668962400001, 834966920275488000001, 113555501157466368000001
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,100
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FORMULA
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a(n) = {n(n+1)/2}*{a(n-1)-1}+1
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EXAMPLE
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a(6) = 1 * 3 * 6 * 10 *15 * 21 + 1 = 56701
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MAPLE
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for n from 1 to 30 do printf(`%d, `, 1+product(j*(j+1)/2, j=1..n)) od:
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PROGRAM
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(PARI) { for (n=1, 100, if (n>1, a=(n*(n + 1)/2)*(a - 1) + 1, a=2); write("b061213.txt", n, " ", a) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jul 19 2009]
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CROSSREFS
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Equals A006472 + 1.
Sequence in context: A058130 A046082 A048774 this_sequence A063458 A132530 A133521
Adjacent sequences: A061210 A061211 A061212 this_sequence A061214 A061215 A061216
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Apr 21 2001
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EXTENSIONS
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More terms from James A. Sellers (sellersj(AT)math.psu.edu), Apr 24 2001
OFFSET changed from 0,1 to 1,1 and EXAMPLE corrected by Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jul 19 2009
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