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 A056147 #12 Dec 12 2017 00:51:10
%S A056147 1,1,4,18,48,360,450,6174,27000,34200,93250,1776566,11293824,
%T A056147 172014648,1296688778,20393895570,173895132784,3328106382492,
%U A056147 11622794050422,287786755919610,709366149217940,17019652496034468,198351459813601270
%N A056147 a(1) = 1, a(m+1) = Sum_{k=1..m} lcm(m, a(k)).
%H A056147 Michael De Vlieger, <a href="/A056147/b056147.txt">Table of n, a(n) for n = 1..506</a>
%e A056147 a(5) = lcm(4,1) + lcm(4,1) + lcm(4,4) + lcm(4,18) = 4 + 4 + 4 + 36 = 48.
%t A056147 Fold[Append[#1, Total@ LCM[#2, #1[[Range@ #2]] ] ] &, {1}, Range@ 22] (* _Michael De Vlieger_, Dec 11 2017 *)
%K A056147 easy,nonn
%O A056147 1,3
%A A056147 _Leroy Quet_, Aug 04 2000