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Search: id:A163756
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| 0, 14, 42, 84, 140, 210, 294, 392, 504, 630, 770, 924, 1092, 1274, 1470, 1680, 1904, 2142, 2394, 2660, 2940, 3234, 3542, 3864, 4200, 4550, 4914, 5292, 5684, 6090, 6510, 6944, 7392, 7854, 8330, 8820, 9324, 9842, 10374, 10920, 11480, 12054, 12642, 13244, 13860
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OFFSET
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0,2
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COMMENT
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14 times the n-th triangular number.
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FORMULA
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a(n)=7*n(n+1) = 14*A000217(n).
G.f.: 14*x/(1-x)^3.
a(n)=14*n+a(n-1)-14 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 12 2009]
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EXAMPLE
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For n=2, a(2)=14*2+0-14=14; n=3, a(3)=14*3+14-14=42; n=4, a(4)=14*4+42-14=84 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 12 2009]
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CROSSREFS
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Cf. A000217.
Sequence in context: A044007 A064512 A118237 this_sequence A005587 A120714 A041378
Adjacent sequences: A163753 A163754 A163755 this_sequence A163757 A163758 A163759
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KEYWORD
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nonn,easy,new
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AUTHOR
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Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 03 2009
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EXTENSIONS
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Extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 06 2009
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