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 A033509 #23 Dec 04 2020 20:51:25
%S A033509 1,13,733,31687,1453535,65805403,2989126727,135658637925,
%T A033509 6158217253688,279533139565077,12688781322524383,575975678462394151,
%U A033509 26145024935911561519,1186789728933332428003,53871436268769248658909
%N A033509 Number of matchings in graph P_{6} X P_{n}.
%D A033509 Per Hakan Lundow, "Computation of matching polynomials and the number of 1-factors in polygraphs", Research reports, No 12, 1996, Department of Mathematics, Umea University.
%H A033509 F. Cazals, <a href="http://algo.inria.fr/libraries/autocomb/MonoDiMer-html/MonoDiMer.html">Monomer-Dimer Tilings</a>, 1997.
%H A033509 David Friedhelm Kind, <a href="https://doi.org/10.13140/RG.2.2.11182.54086">The Gunport Problem: An Evolutionary Approach</a>, De Montfort University (Leicester, UK, 2020).
%H A033509 Per Hakan Lundow, <a href="http://www.theophys.kth.se/~phl/Text/1factors2.ps.gz">Enumeration of matchings in polygraphs</a>, 1998.
%F A033509 G.f.: (1 -23*x -311*x^2 +3891*x^3 +12057*x^4 -218447*x^5 +315889*x^6 +2997721*x^7 -8754480*x^8 -13467571*x^9 +66016499*x^10 +14684235*x^11 -240612231*x^12 +56233657*x^13 +496137395*x^14 -207743591*x^15 -612805499*x^16 +303976032*x^17 +458919487*x^18 -249194245*x^19 -206819317*x^20 +123372421*x^21 +54160427*x^22 -37223601*x^23 -7443809*x^24 +6708699*x^25 +338040*x^26 -686517*x^27 +29377*x^28 +36273*x^29 -3521*x^30 -861*x^31 +109*x^32 +7*x^33 -x^34) / (1 -36*x -576*x^2 +6080*x^3 +42422*x^4 -453004*x^5 -443404*x^6 +12931566*x^7 -25517604*x^8 -83558644*x^9 +295510396*x^10 +154307596*x^11 -1335612340*x^12 +274712602*x^13 +3235975264*x^14 -1630080704*x^15 -4669345206*x^16 +2978277152*x^17 +4169343006*x^18 -2919950172*x^19 -2310327672*x^20 +1717916424*x^21 +777289050*x^22 -626694028*x^23 -149620588*x^24 +141424642*x^25 +13835164*x^26 -19237868*x^27 -94620*x^28 +1503868*x^29 -81796*x^30 -62874*x^31 +5736*x^32 +1224*x^33 -138*x^34 -8*x^35 +x^36). - _Sergey Perepechko_, May 04 2013
%Y A033509 Column 6 of triangle A210662.
%Y A033509 Bisection (even part) gives A260035.
%K A033509 nonn
%O A033509 0,2
%A A033509 _Per H. Lundow_