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 A168278 #21 Sep 08 2022 08:45:48
%S A168278 2,7,7,12,12,17,17,22,22,27,27,32,32,37,37,42,42,47,47,52,52,57,57,62,
%T A168278 62,67,67,72,72,77,77,82,82,87,87,92,92,97,97,102,102,107,107,112,112,
%U A168278 117,117,122,122,127,127,132,132,137,137,142,142,147,147,152,152,157
%N A168278 (10*n + 5*(-1)^n + 3)/4.
%H A168278 Vincenzo Librandi, <a href="/A168278/b168278.txt">Table of n, a(n) for n = 1..1000</a>
%H A168278 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,-1).
%F A168278 G.f.: x*(2 + 5*x - 2*x^2)/( (1+x)*(x-1)^2 ). - _R. J. Mathar_, Jan 05 2011
%F A168278 a(n) = A016873(floor(n/2)). - _R. J. Mathar_, Jan 05 2011
%F A168278 a(n) = A168282(n) + 1. - _Bruno Berselli_, Sep 16 2013
%F A168278 E.g.f.: (1/4)*(5 - 8*exp(x) + (3 + 10*x)*exp(2*x))*exp(-x). - _G. C. Greubel_, Jul 16 2016
%t A168278 Table[5 n/2 + 3/4 + 5 (-1)^n/4, {n, 70}] (* _Bruno Berselli_, Sep 16 2013 *)
%t A168278 CoefficientList[Series[- (- 2 - 5 x + 2 x^2) / ((1 + x) (x - 1)^2), {x, 0, 70}], x] (* _Vincenzo Librandi_, Sep 16 2013 *)
%o A168278 (Magma) [5*n/2+3/4+5*(-1)^n/4: n in [1..70]]; // _Vincenzo Librandi_, Sep 16 2013
%Y A168278 Cf. A016873, A168282.
%K A168278 nonn,easy
%O A168278 1,1
%A A168278 _Vincenzo Librandi_, Nov 22 2009
%E A168278 New definition by _R. J. Mathar_, Jan 05 2011