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 A025570 #6 Sep 07 2019 22:03:31 %S A025570 1,2,8,40,211,1148,6369,35816,203424,1164228,6703372,38785840, %T A025570 225325940,1313494396,7679038865,45006411960,264357297375, %U A025570 1555762562100,9171399730944,54148782940112,320136500713070,1895036382245032,11230166960501463,66619011999761208,395563260817743219 %N A025570 a(n) = T(2n,n), where T is the array defined in A025564. %K A025570 nonn %O A025570 1,2 %A A025570 _Clark Kimberling_ %E A025570 More terms from _Sean A. Irvine_, Sep 07 2019