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 A091052 #15 Jun 01 2017 05:07:09
%S A091052 1,2,13,26,205,410,3277,6554,52429,104858,838861,1677722,13421773,
%T A091052 26843546,214748365,429496730,3435973837,6871947674,54975581389,
%U A091052 109951162778,879609302221,1759218604442,14073748835533,28147497671066
%N A091052 Record values in A091023.
%H A091052 Indranil Ghosh, <a href="/A091052/b091052.txt">Table of n, a(n) for n = 1..1000</a>
%H A091052 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,17,0,-16)
%F A091052 Add 1 to every term of A077854, then take the terms with indices 4k and 4k+3.
%F A091052 (1/20) [3*4^n - (-4)^n + 2*(-1)^n + 6]. - _Ralf Stephan_, Dec 02 2004
%F A091052 G.f. -x*(2*x-1)*(1+2*x)^2 / ( (x-1)*(4*x-1)*(4*x+1)*(1+x) ). - _R. J. Mathar_, Jun 10 2013
%t A091052 LinearRecurrence[{0,17,0,-16},{1,2,13,26},24] (* _Indranil Ghosh_, Feb 22 2017 *)
%o A091052 (Python) def A091052(n): return (3*4**n-(-4)**n+2*(-1)**n+6)/20 # _Indranil Ghosh_, Feb 22 2017
%o A091052 (PARI) a(n)=(3*4^n - (-4)^n + 2*(-1)^n + 6)/20 \\ _Charles R Greathouse IV_, Feb 22 2017
%Y A091052 Cf. A091023, A091053.
%K A091052 nonn,easy
%O A091052 1,2
%A A091052 _N. J. A. Sloane_, Feb 23 2004
%E A091052 More terms from _David Wasserman_, Feb 23 2006