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Search: id:A152773
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| A152773 |
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3 times heptagonal numbers: 3n(5n-3)/2. |
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+0
3
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| 0, 3, 21, 54, 102, 165, 243, 336, 444, 567, 705, 858, 1026, 1209, 1407, 1620, 1848, 2091, 2349, 2622, 2910, 3213, 3531, 3864, 4212, 4575, 4953, 5346, 5754, 6177, 6615, 7068, 7536, 8019, 8517, 9030, 9558, 10101, 10659, 11232, 11820
(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) = (15n^2 - 9n)/2 = A000566(n)*3.
a(n)=15*n+a(n-1)-27 (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)=15*2+0-27=3; n=3, a(3)=15*3+3-27=21; n=4, a(4)=15*4+21-27=54 [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, 3, 6!, 15}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Apr 02 2009]
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CROSSREFS
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Cf. A000566, A135706.
Sequence in context: A146712 A034186 A027499 this_sequence A039595 A033567 A162394
Adjacent sequences: A152770 A152771 A152772 this_sequence A152774 A152775 A152776
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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 13 2008
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