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A153780
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10 times pentagonal numbers: 5n(3n-1).
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0
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0, 10, 50, 120, 220, 350, 510, 700, 920, 1170, 1450, 1760, 2100, 2470, 2870, 3300, 3760, 4250, 4770, 5320, 5900, 6510, 7150, 7820, 8520, 9250, 10010, 10800, 11620, 12470, 13350, 14260, 15200, 16170, 17170, 18200, 19260, 20350
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OFFSET
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0,2
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LINKS
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Table of n, a(n) for n=0..37.
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FORMULA
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a(n) = 15n^2 - 5n = A000326(n)*10 = A049450(n)*5 = A152734(n)*2.
a(n)=30*n+a(n-1)-20 (with a(0)=0). [From Vincenzo Librandi, Aug 03 2010]
G.f.: 10*x*(1+2*x)/(1-x)^3. [Colin Barker, Feb 14 2012]
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EXAMPLE
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a(1)=30*1+0-20=10; a(2)=30*2+10-20=50; a(3)=30*3+50-20=120 [From Vincenzo Librandi, Aug 03 2010]
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CROSSREFS
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Cf. A000326, A049450, A152734, A152996, A153449.
Sequence in context: A036786 A085444 A102915 * A196507 A008531 A051230
Adjacent sequences: A153777 A153778 A153779 * A153781 A153782 A153783
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KEYWORD
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easy,nonn
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AUTHOR
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Omar E. Pol, Jan 01 2009
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STATUS
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approved
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