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Search: id:A069132
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| A069132 |
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Centered 19-gonal numbers. |
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+0
6
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| 1, 20, 58, 115, 191, 286, 400, 533, 685, 856, 1046, 1255, 1483, 1730, 1996, 2281, 2585, 2908, 3250, 3611, 3991, 4390, 4808, 5245, 5701, 6176, 6670, 7183, 7715, 8266, 8836, 9425, 10033, 10660, 11306, 11971, 12655, 13358, 14080, 14821, 15581, 16360, 17158
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Except for the first term, a(n)=19*n+a(n-1), (with a(1)=20) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 24 2009]
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LINKS
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E. Weisstein, Centered Polygonal Numbers
Index entries for sequences related to centered polygonal numbers
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FORMULA
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a(n) = (19n^2 - 19n + 2)/2.
a(n)=19*n+a(n-1)-19 (with a(1)=1) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 16 2009]
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EXAMPLE
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a(5)= 191 because (19*5^2 - 19*5 + 2)/2 = (475 - 95 + 2)/2 = 382/2 = 191.
For n=2, a(2)=19*2+1-19=20; n=3, a(3)=19*3+20-19=58; n=4, a(4)=19*4+58-19=115 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 16 2009]
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CROSSREFS
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Cf. A005448, A001844, A005891, A003215, A069099.
Sequence in context: A012483 A051872 A104100 this_sequence A124713 A126374 A163761
Adjacent sequences: A069129 A069130 A069131 this_sequence A069133 A069134 A069135
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KEYWORD
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easy,nice,nonn,new
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AUTHOR
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Terrel Trotter, Jr. (ttrotter(AT)telesal.net), Apr 07 2002
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EXTENSIONS
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More terms from Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 24 2009
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