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Search: id:A142463
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| -1, 3, 11, 23, 39, 59, 83, 111, 143, 179, 219, 263, 311, 363, 419, 479, 543, 611, 683, 759, 839, 923, 1011, 1103, 1199, 1299, 1403, 1511, 1623, 1739, 1859, 1983, 2111, 2243, 2379, 2519, 2663, 2811, 2963, 3119, 3279, 3443, 3611, 3783, 3959, 4139, 4323, 4511, 4703, 4899, 5099
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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All entries are odd.
Numbers n such that 2n+3 is square. [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Jan 28 2009]
First diagonal A144562. [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Jan 28 2009]
Essentially the same as A132209.
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FORMULA
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a(n) = a(n-1)+4*n.
G.f.: (1-6x+x^2)/(1-x)^3; a(n)=4*C(n+1,2)-1. [From Paul Barry (pbarry(AT)wit.ie), Nov 03 2009]
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MATHEMATICA
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a[0] = -1; a[n_] := a[n] = a[n - 1] + n; Table[a[n], {n, 0, 30}]; f[n_] := 4*a[n] + 3; Table[f[n], {n, 0, 50}] - Roger L. Bagula and Gary W. Adamson (rlbagulatftn(AT)yahoo.com), Oct 20 2008
Array[ -#*(2-#*2)-1&, 5!, 1] [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Dec 21 2008]
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CROSSREFS
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Cf. A132209, A000096.
Sequence in context: A119173 A106201 A132209 this_sequence A086497 A121509 A096071
Adjacent sequences: A142460 A142461 A142462 this_sequence A142464 A142465 A142466
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KEYWORD
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sign,easy,new
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AUTHOR
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Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Sep 19 2008
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EXTENSIONS
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More terms from Roger L. Bagula and Gary W. Adamson (rlbagulatftn(AT)yahoo.com), Oct 20 2008
Edited by the Associate Editors of the OEIS, Sep 02 2009
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