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 A268581 #59 Sep 08 2022 08:46:15
%S A268581 5,15,29,47,69,95,125,159,197,239,285,335,389,447,509,575,645,719,797,
%T A268581 879,965,1055,1149,1247,1349,1455,1565,1679,1797,1919,2045,2175,2309,
%U A268581 2447,2589,2735,2885,3039,3197,3359,3525,3695,3869,4047,4229,4415,4605
%N A268581 a(n) = 2*n^2 + 8*n + 5.
%C A268581 Also, numbers m such that 2*m + 6 is a square.
%C A268581 All the terms end with a digit in {5, 7, 9}, or equivalently, are congruent to {5, 7, 9} mod 10. - _Stefano Spezia_, Aug 05 2021
%H A268581 Stefano Spezia, <a href="/A268581/b268581.txt">Table of n, a(n) for n = 0..10000</a>
%H A268581 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A268581 From _Vincenzo Librandi_, Apr 13 2016: (Start)
%F A268581 G.f.: (5-x^2)/(1-x)^3.
%F A268581 a(n) = 2*(n+2)^2 - 3.
%F A268581 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). (End)
%F A268581 E.g.f.: exp(x)*(5 + 10*x + 2*x^2). - _Stefano Spezia_, Aug 03 2021
%t A268581 Table[2 n^2 + 8 n + 5, {n, 0, 50}] (* _Vincenzo Librandi_, Apr 13 2016 *)
%t A268581 LinearRecurrence[{3,-3,1},{5,15,29},50] (* _Harvey P. Dale_, Jan 18 2017 *)
%o A268581 (Magma) [2*n^2+8*n+5: n in [0..60]];
%o A268581 (Magma) [n: n in [0..6000] | IsSquare(2*n+6)];
%o A268581 (PARI) lista(nn) = for(n=0, nn, print1(2*n^2+8*n+5, ", ")); \\ _Altug Alkan_, Apr 10 2016
%o A268581 (Sage) [2*n^2 + 8*n + 5 for n in [0..46]] # _Stefano Spezia_, Aug 04 2021
%Y A268581 Cf. numbers n such that 2*n + k is a perfect square: A093328 (k=-6), A097080 (k=-5), no sequence (k=-4), A051890 (k=-3), A058331 (k=-2), A001844 (k=-1), A001105 (k=0), A046092 (k=1), A056222 (k=2), A142463 (k=3), A054000 (k=4), A090288 (k=5), this sequence (k=6), A059993 (k=7), A147973 (k=8), A139570 (k=9), no sequence (k=10), A222182 (k=11), A152811 (k=12), A181570 (k=13).
%K A268581 nonn,easy
%O A268581 0,1
%A A268581 _Juri-Stepan Gerasimov_, Apr 10 2016
%E A268581 Changed offset from 1 to 0, adapted formulas and programs by _Bruno Berselli_, Apr 13 2016