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Search: id:A153780
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| A153780 |
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10 times pentagonal numbers: 5n(3n-1). |
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+0
1
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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
(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 - 5n = A000326(n)*10 = A049450(n)*5 = A152734(n)*2.
a(n)=30*n+a(n-1)-50 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 15 2009]
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EXAMPLE
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For n=2, a(2)=30*2+0-50=10; n=3, a(3)=30*3+10-50=50; n=4, a(4)=30*4+50-50=120 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 15 2009]
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CROSSREFS
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Cf. A000326, A049450, A152734, A152996, A153449.
Sequence in context: A036786 A085444 A102915 this_sequence A008531 A051230 A008413
Adjacent sequences: A153777 A153778 A153779 this_sequence A153781 A153782 A153783
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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), Jan 01 2009
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