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 A025572 #6 Sep 07 2019 22:03:06 %S A025572 1,4,34,330,3381,35700,384307,4193020,46203670,513011312,5730482707, %T A025572 64324536822,724966763955,8198552413800,92985865982415, %U A025572 1057267681773972,12047638469222921,137547814582468048,1573060924386848400,18017644508154675426,206653990802794950415 %N A025572 a(n) = T(4n,n), where T is the array defined in A025564. %K A025572 nonn %O A025572 1,2 %A A025572 _Clark Kimberling_ %E A025572 More terms from _Sean A. Irvine_, Sep 07 2019