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 A102147 #14 Jan 15 2021 07:36:56
%S A102147 1,1,5,35,315,3465,45045,675675,11486475,218243025,4583103525,
%T A102147 105411381075,2635284526875,71152682225625,2063427784543125,
%U A102147 63966261320836875,2110886623587616875,73881031825566590625
%N A102147 Second Eulerian transform of 1, 2, 3, 4, 5, ... (A000027).
%D A102147 R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics. Addison-Wesley, Reading, MA, 1990, p. 256.
%F A102147 a(n) = Sum_{k=0..n} E(n,k) A000027(k), where E(n,k) is a second-order Eulerian number (A008517).
%Y A102147 Cf. A001147, A008517.
%Y A102147 Apparently equals A051577(n-2), n > 1.
%K A102147 nonn
%O A102147 1,3
%A A102147 _Ross La Haye_, Feb 14 2005