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Search: id:A152744
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| A152744 |
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7 times pentagonal numbers: 7n(3n-1)/2. |
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+0
3
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| 0, 7, 35, 84, 154, 245, 357, 490, 644, 819, 1015, 1232, 1470, 1729, 2009, 2310, 2632, 2975, 3339, 3724, 4130, 4557, 5005, 5474, 5964, 6475, 7007, 7560, 8134, 8729, 9345, 9982, 10640, 11319, 12019, 12740, 13482, 14245, 15029
(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) = (21n^2 - 7n)/2 = A000326(n)*7.
a(n)=21*n+a(n-1)-35 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 13 2009]
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EXAMPLE
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For n=2, a(2)=21*2+0-35=7; n=3, a(3)=21*3+7-35=35: n=4, a(4)=21*4+35-35=84 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 13 2009]
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MATHEMATICA
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s=0; lst={s}; Do[s+=n; AppendTo[lst, s], {n, 7, 7!, 21}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Apr 03 2009]
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CROSSREFS
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Cf. A000326, A014642, A152743.
Sequence in context: A000829 A061825 A077536 this_sequence A130884 A037092 A015667
Adjacent sequences: A152741 A152742 A152743 this_sequence A152745 A152746 A152747
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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), Dec 12 2008
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