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Search: id:A153785
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| A153785 |
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5 times heptagonal numbers: 5n(5n-3)/2. |
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+0
2
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| 0, 5, 35, 90, 170, 275, 405, 560, 740, 945, 1175, 1430, 1710, 2015, 2345, 2700, 3080, 3485, 3915, 4370, 4850, 5355, 5885, 6440, 7020, 7625, 8255, 8910, 9590, 10295, 11025, 11780, 12560, 13365, 14195, 15050, 15930, 16835, 17765
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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a(n) = (25n^2 - 15n)/2 = A000566(n)*5.
a(n)=25*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)=25*2+0-45=5; n=3, a(3)=25*3+5-45=35; n=4, a(4)=25*4+35-45=90 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 14 2009]
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MATHEMATICA
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s=0; lst={s}; Do[s+=n; AppendTo[lst, s], {n, 5, 8!, 25}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Apr 03 2009]
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CROSSREFS
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Cf. A000566, A153784, A154786.
Sequence in context: A115707 A117793 A145920 this_sequence A090294 A162540 A161199
Adjacent sequences: A153782 A153783 A153784 this_sequence A153786 A153787 A153788
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KEYWORD
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easy,nonn,new
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AUTHOR
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Omar E. Pol (info(AT)polprimos.com), Jan 07 2009
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