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A144390
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a(n) = 3*n^2 - n - 1.
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10
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1, 9, 23, 43, 69, 101, 139, 183, 233, 289, 351, 419, 493, 573, 659, 751, 849, 953, 1063, 1179, 1301, 1429, 1563, 1703, 1849, 2001, 2159, 2323, 2493, 2669, 2851, 3039, 3233, 3433, 3639, 3851, 4069, 4293, 4523, 4759, 5001, 5249, 5503, 5763, 6029, 6301, 6579
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OFFSET
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1,2
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COMMENTS
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Sequence's original Name was "First bisection of A135370."
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
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a(n+1) = a(n) + 6*n + 2; see A016933.
a(n) = 3*n^2 - n - 1. - Paolo P. Lava, Oct 06 2008
G.f.: x*(1+6*x-x^2)/(1-x)^3. a(n) = A049450(n)-1. - R. J. Mathar, Oct 24 2008
a(-n) = A144391(n). - Michael Somos, Mar 27 2014
E.g.f.: (3*x^2 + 2*x -1)*exp(x) + 1. - G. C. Greubel, Jul 19 2017
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MAPLE
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A144390:=n->3*n^2-n-1; seq(A144390(n), n=1..50); # Wesley Ivan Hurt, Mar 26 2014
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MATHEMATICA
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s=-1; lst={}; Do[s+=n+1; AppendTo[lst, s], {n, 1, 6!, 6}]; lst (* Vladimir Joseph Stephan Orlovsky, Oct 25 2008 *)
Table[3*n^2 -n -1 , {n, 0, 50}] (* G. C. Greubel, Jul 19 2017 *)
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PROG
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(MAGMA) [3*n^2-n-1: n in [1..60]]; // Vincenzo Librandi, Jun 14 2011
(PARI) a(n)=3*n^2-n-1 \\ Charles R Greathouse IV, Oct 07 2015
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CROSSREFS
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Cf. A016933.
Sequence in context: A054302 A147395 A302906 * A024843 A183453 A296311
Adjacent sequences: A144387 A144388 A144389 * A144391 A144392 A144393
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KEYWORD
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nonn,easy
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AUTHOR
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Paul Curtz, Oct 02 2008
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EXTENSIONS
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Edited by R. J. Mathar, Oct 24 2008
More terms from Vladimir Joseph Stephan Orlovsky, Oct 25 2008
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STATUS
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approved
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