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 A108928 #26 Sep 08 2022 08:45:19
%S A108928 5,29,69,125,197,285,389,509,645,797,965,1149,1349,1565,1797,2045,
%T A108928 2309,2589,2885,3197,3525,3869,4229,4605,4997,5405,5829,6269,6725,
%U A108928 7197,7685,8189,8709,9245,9797,10365,10949,11549,12165,12797,13445,14109,14789
%N A108928 a(n) = 8*n^2 - 3.
%C A108928 Sequence found by reading the segment (5, 29) together with the line from 29, in the direction 29, 69,..., in the square spiral whose vertices are the triangular numbers A000217. - _Omar E. Pol_, Sep 04 2011
%H A108928 Vincenzo Librandi, <a href="/A108928/b108928.txt">Table of n, a(n) for n = 1..10000</a>
%H A108928 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A108928 a(n) = 2*(2*n-1)*(2*n+1)-1.
%F A108928 a(1)=5, a(2)=29, a(3)=69, a(n)=3*a(n-1)-3*a(n-2)+a(n-3). - _Harvey P. Dale_, Jul 21 2012
%F A108928 From _G. C. Greubel_, Jul 15 2017:(Start)
%F A108928 G.f.: x*(-5 - 14*x + 3*x^2)/(-1 + x)^3.
%F A108928 E.g.f.: (8*x^2 + 8*x - 3)*exp(x) + 3. (End)
%e A108928 (1*3 = 3)+2 = 5; (3*5 = 15)+14 = 29; (5*7 = 35)+34 = 69; (7*9 = 63)+62 = 125; ...
%p A108928 seq(8*n^2-3,n=1..50); # _Emeric Deutsch_, Aug 01 2005
%t A108928 8*Range[50]^2-3 (* or *) LinearRecurrence[{3,-3,1},{5,29,69},50] (* _Harvey P. Dale_, Jul 21 2012 *)
%o A108928 (PARI) a(n)=8*n^2-3 \\ _Charles R Greathouse IV_, Sep 04 2011
%o A108928 (Magma) [8*n^2 - 3: n in [1..50]]; // _Vincenzo Librandi_, Sep 05 2011
%K A108928 easy,nonn
%O A108928 1,1
%A A108928 Marcel Hetkowski Fabeny (marcelfabeny(AT)yahoo.com.br), Jul 19 2005
%E A108928 More terms from _Emeric Deutsch_, Aug 01 2005