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A152773
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3 times heptagonal numbers: 3n(5n-3)/2.
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12
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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; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| Index entries for sequences related to linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
| a(n) = (15n^2 - 9n)/2 = A000566(n)*3.
a(n)=a(n-1)+15*n-12 (with a(0)=0) [From Vincenzo Librandi, Nov 26 2010]
G.f.: 3*x*(1+4*x)/(1-x)^3. - Bruno Berselli, Jan 21 2011
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MATHEMATICA
| 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
| Cf. A000566, A135706.
3 times n-gonal numbers: A045943, A033428, A062741, A094159, A152751, A152759, A152767, A153783, A153448, A153875.
Sequence in context: A146712 A034186 A027499 * A039595 A033567 A181156
Adjacent sequences: A152770 A152771 A152772 * A152774 A152775 A152776
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KEYWORD
| easy,nonn
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AUTHOR
| Omar E. Pol (info(AT)polprimos.com), Dec 13 2008
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