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 A173260 #10 Jun 20 2021 13:20:14 %S A173260 1,5,25,125,15625,244140625,59604644775390625, %T A173260 3552713678800500929355621337890625, %U A173260 12621774483536188886587657044524579674771302961744368076324462890625 %N A173260 a(0)=1, a(1)=5; for n>=2, a(n) = 5^A042950(n-2). %Y A173260 Cf. A042950, A167182, A172489, A175129. %K A173260 nonn %O A173260 0,2 %A A173260 _Giovanni Teofilatto_, Feb 24 2010 %E A173260 Revised by _N. J. A. Sloane_, Jun 20 2021