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 A093147 #9 Sep 03 2019 02:29:37 %S A093147 1,15,250,4250,72500,1237500,21125000,360625000,6156250000, %T A093147 105093750000,1794062500000,30626562500000,522828125000000, %U A093147 8925234375000000,152363281250000000,2601003906250000000,44401914062500000000 %N A093147 Third binomial transform of Pell(3n+1). %H A093147 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (20,-50). %F A093147 G.f.: (1-5*x)/(1 - 20*x + 50*x^2); %F A093147 a(n) = ((1 + sqrt(2))*(10 + 5*sqrt(2))^n - (1 - sqrt(2))*(10-5*sqrt(2))^n)/(2*sqrt(2)). %Y A093147 Cf. A000129, A093144, A093146. %K A093147 easy,nonn %O A093147 0,2 %A A093147 _Paul Barry_, Mar 26 2004