This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A239794 #26 May 30 2025 19:33:03
%S A239794 -6,13,42,81,130,189,258,337,426,525,634,753,882,1021,1170,1329,1498,
%T A239794 1677,1866,2065,2274,2493,2722,2961,3210,3469,3738,4017,4306,4605,
%U A239794 4914,5233,5562,5901,6250,6609,6978,7357,7746,8145,8554,8973,9402,9841,10290
%N A239794 5*n^2 + 4*n - 15.
%C A239794 Follows the integer values from 1 on the quadratic equation 5*x^2 + 4*n - 15, this is the case x=n.
%H A239794 Vincenzo Librandi, <a href="/A239794/b239794.txt">Table of n, a(n) for n = 1..1000</a>
%H A239794 WolframAlpha, <a href="https://www.wolframalpha.com/share/clip?f=d41d8cd98f00b204e9800998ecf8427enfege9ojn3">Table of 5n^2+4n-15</a>
%H A239794 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A239794 From _Bruno Berselli_, Mar 27 2014: (Start)
%F A239794 G.f.: -x*(6 - 31*x + 15*x^2)/(1 - x)^3.
%F A239794 a(n+1) - a(n) = A017377(n).
%F A239794 a(n) - a(-n) = A008590(n). (End)
%e A239794 For n=3, a(3) = 5*3^2 + 4*3 - 15 = 42; for n=6, a(6) = 5*6^2 + 4*6 - 15 = 189.
%t A239794 Table[5 n^2 + 4 n - 15, {n, 50}]
%t A239794 CoefficientList[Series[(6 - 31 x + 15 x^2)/(x - 1)^3, {x, 0, 50}], x] (* _Vincenzo Librandi_, Mar 29 2014 *)
%t A239794 LinearRecurrence[{3,-3,1},{-6,13,42},50] (* _Harvey P. Dale_, May 30 2025 *)
%o A239794 (Magma) [5*n^2+4*n-15: n in [1..50]];
%o A239794 (PARI) a(n)=5*n^2+4*n-15 \\ _Charles R Greathouse IV_, Jun 17 2017
%Y A239794 Cf. A008590, A017377.
%K A239794 sign,easy
%O A239794 1,1
%A A239794 _Katherine Guo_, Mar 26 2014