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 A339226 #7 Nov 30 2020 08:56:27
%S A339226 2,7,32,176,1066,6935,47216,332700,2404818,17734668,132901644,
%T A339226 1009161505,7747608480,60037905076,468987635982,3689066578347,
%U A339226 29195587558726,232303316402615,1857264782113562,14912673794505898,120203145484455930,972291038495626309
%N A339226 Number of oriented series-parallel networks with n elements of 2 colors.
%C A339226 See A339228 for additional details.
%e A339226 In the following examples elements in series are juxtaposed and elements in parallel are separated by '|'.
%e A339226 a(1) = 2: (1), (2).
%e A339226 a(2) = 7: (11), (12), (21), (22), (1|1), (1|2), (2|2).
%o A339226 (PARI) \\ See A339228 for R(n,k).
%o A339226 seq(n) = {R(n,2)}
%Y A339226 Cf. A003430, A339227, A339228.
%K A339226 nonn
%O A339226 1,1
%A A339226 _Andrew Howroyd_, Nov 28 2020