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 A026918 #11 Jun 13 2015 00:49:06
%S A026918 1,13,41,90,185,335,601,1020,1729,2857,4721,7710,12593,20459,33241,
%T A026918 53880,87337,141421,229001,370650,599921,970823,1571041,2542140,
%U A026918 4113505,6655945,10769801,17426070,28196249,45622667
%N A026918 Sum{T(n-k,k)}, 0<=k<=[ n/2 ], T given by A026907.
%H A026918 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (1,3,-2,-3,1,1).
%F A026918 8*Fibonacci(n+5) + (3/4)*[(n-1)(-1)^n - 17(n+3)]. - _Ralf Stephan_, May 13 2004
%F A026918 G.f. ( -1-12*x-25*x^2-12*x^3-x^4 ) / ( (x^2+x-1)*(x-1)^2*(1+x)^2 ). - _R. J. Mathar_, May 22 2013
%t A026918 LinearRecurrence[{1,3,-2,-3,1,1},{1,13,41,90,185,335},30] (* _Harvey P. Dale_, Jan 08 2015 *)
%K A026918 nonn
%O A026918 0,2
%A A026918 _Clark Kimberling_