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a(n) = 2*n^2 + 9*n - 5.
0

%I #24 Jun 02 2021 03:59:40

%S 6,21,40,63,90,121,156,195,238,285,336,391,450,513,580,651,726,805,

%T 888,975,1066,1161,1260,1363,1470,1581,1696,1815,1938,2065,2196,2331,

%U 2470,2613,2760,2911,3066,3225,3388,3555,3726,3901,4080,4263,4450,4641,4836,5035

%N a(n) = 2*n^2 + 9*n - 5.

%D Michael Serra, Discovering geometry: an inductive approach, 2nd ed., Berkeley, Calif.: Key Curriculum Press, 1997, p. 61, Problem 8.

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).

%t Table[2n^2+9n-5,{n,50}] (* _Harvey P. Dale_, May 30 2021 *)

%K nonn,easy,less

%O 1,1

%A Pam Smith (homelizard(AT)aol.com), Aug 20 2000

%E Name clarified by Editors of OEIS, May 24 2021

%E More terms from _Harvey P. Dale_, May 30 2021