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0, 7, 20, 39, 64, 95, 132, 175, 224, 279, 340, 407, 480, 559, 644, 735, 832, 935, 1044, 1159, 1280, 1407, 1540, 1679, 1824, 1975, 2132, 2295, 2464, 2639, 2820, 3007, 3200, 3399, 3604, 3815, 4032, 4255, 4484, 4719, 4960, 5207, 5460
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n)=3*n^2 + 4n.
a(n)=6*n+a(n-1)+1 (with a(0)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 03 2010]
G.f.: x*(7 - x)/(1 - x)^3. [Arkadiusz Wesolowski, Dec 24 2011]
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EXAMPLE
| a(1)=6*1+0+1=7; a(2)=6*2+7+1=20; a(3)=6*3+20+1=39 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 03 2010]
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MATHEMATICA
| lst={}; Do[AppendTo[lst, n*(3*n+4)], {n, 0, 6!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 06 2008]
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CROSSREFS
| Cf. A033428, A045944, A067725, A140677, A140678, A067707, A140679, A140680, A140681, A140689.
Sequence in context: A200773 A063235 A063151 * A025056 A038349 A100752
Adjacent sequences: A140673 A140674 A140675 * A140677 A140678 A140679
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KEYWORD
| easy,nonn
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AUTHOR
| Omar E. Pol (info(AT)polprimos.com), May 22 2008
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