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A153793
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13 times pentagonal numbers: 13n(3n-1)/2.
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1
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0, 13, 65, 156, 286, 455, 663, 910, 1196, 1521, 1885, 2288, 2730, 3211, 3731, 4290, 4888, 5525, 6201, 6916, 7670, 8463, 9295, 10166, 11076, 12025, 13013, 14040, 15106, 16211, 17355, 18538, 19760, 21021, 22321, 23660, 25038, 26455
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n) = (39n^2 - 13n)/2 = A000326(n)*13.
a(n)=39*n+a(n-1)-26 (with a(0)=0). [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 03 2010]
G.f.: 13*x*(1+2*x)/(1-x)^3. [Colin Barker, Feb 14 2012]
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EXAMPLE
| a(1)=39*1+0-26=13; a(2)=39*2+13-26=65; a(3)=39*3+65-26=156 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 03 2010]
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CROSSREFS
| Cf. A000326, A153792.
Sequence in context: A169883 A010820 A022705 * A067160 A147067 A147075
Adjacent sequences: A153790 A153791 A153792 * A153794 A153795 A153796
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KEYWORD
| easy,nonn,changed
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AUTHOR
| Omar E. Pol (info(AT)polprimos.com), Jan 01 2009
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