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 A135246 #13 Dec 30 2023 22:11:54
%S A135246 1,3,5,7,11,17,27,41,65,99,157,239,379,577,915,1393,2209,3363,5333,
%T A135246 8119,12875,19601,31083,47321,75041,114243,181165,275807,437371,
%U A135246 665857,1055907,1607521,2549185,3880899,6154277,9369319,14857739,22619537,35869755,54608393,86597249,131836323,209064253,318281039,504725755,768398401,1218515763,1855077841,2941757281,4478554083
%N A135246 Shifted Pell recurrence: a(n) = 2*a(n-2) + a(n-4).
%C A135246 Mix A048655(n) and A001333(n+2).
%H A135246 G. C. Greubel, <a href="/A135246/b135246.txt">Table of n, a(n) for n = 0..1000</a>
%H A135246 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,2,0,1).
%F A135246 G.f.: (1 + 3*x + 3*x^2 + x^3)/(1 - 2*x^2 - x^4). - _G. C. Greubel_, Oct 04 2016
%F A135246 a(n) = 2*a(n-2) + a(n-4). - _Wesley Ivan Hurt_, Dec 30 2023
%t A135246 LinearRecurrence[{0, 2, 0, 1}, {1, 3, 5, 7}, 25] (* _G. C. Greubel_, Oct 04 2016 *)
%o A135246 (PARI) Vec((1 + 3*x + 3*x^2 + x^3)/(1 - 2*x^2 - x^4) + O(x^50)) \\ _Michel Marcus_, Oct 05 2016
%Y A135246 Cf. A001333, A048655, A109543.
%K A135246 nonn,easy
%O A135246 0,2
%A A135246 _Paul Curtz_, Feb 15 2008