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Search: id:A152996
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| A152996 |
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9 times pentagonal numbers: 9n(3n-1)/2. |
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+0
3
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| 0, 9, 45, 108, 198, 315, 459, 630, 828, 1053, 1305, 1584, 1890, 2223, 2583, 2970, 3384, 3825, 4293, 4788, 5310, 5859, 6435, 7038, 7668, 8325, 9009, 9720, 10458, 11223, 12015, 12834, 13680, 14553, 15453, 16380, 17334, 18315, 19323
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OFFSET
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0,2
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FORMULA
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a(n) = (27n^2 - 9n)/2 = A000326(n)*9 = A062741(n)*3.
a(n)=27*n+a(n-1)-45 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 14 2009]
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EXAMPLE
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For n=2, a(2)=27*2+0-45=9; n=3, a(3)=27*3+9-45=45; n=4, a(4)=27*4+45-45=108 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 14 2009]
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CROSSREFS
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Cf. A000326, A062741.
Sequence in context: A067536 A139609 A068314 this_sequence A060008 A095166 A126899
Adjacent sequences: A152993 A152994 A152995 this_sequence A152997 A152998 A152999
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KEYWORD
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easy,nonn
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AUTHOR
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Omar E. Pol (info(AT)polprimos.com), Dec 22 2008
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