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 A186417 #13 Jun 02 2025 03:55:04
%S A186417 1,0,1,2,3,4,8,10,17,24,36,50,76,102,148,204,285,386,537,718,980,1308,
%T A186417 1756,2324,3097,4060,5353,6986,9124,11822,15341,19748,25442,32586,
%U A186417 41705,53124,67628,85692,108501,136870,172430,216528,271578,339578,424073
%N A186417 The number of unlabeled graphs on n nodes with degree of 1 or 2.
%C A186417 The partial sums give the number of unlabeled graphs on n nodes of degree 0, 1, or 2.
%D A186417 Herbert S. Wilf, Generatingfunctiontology, Academic Press, p. 106.
%H A186417 Andrew Howroyd, <a href="/A186417/b186417.txt">Table of n, a(n) for n = 0..1000</a>
%F A186417 O.g.f.: (1/(1-x^2)) * Product_{i>=3} 1/(1-x^i)^2.
%t A186417 CoefficientList[Series[1/(1-x^2) Product[1/(1-x^i)^2,{i,3,20}],{x,0,20}],x]
%o A186417 (PARI) seq(n)={Vec(prod(i=3, n, 1/(1-x^i)^2 + O(x*x^n))/(1-x^2))} \\ _Andrew Howroyd_, Oct 20 2018
%K A186417 nonn
%O A186417 0,4
%A A186417 _Geoffrey Critzer_, Feb 21 2011
%E A186417 Terms a(21) and beyond from _Andrew Howroyd_, Oct 20 2018