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 A007200 M4838 #16 Nov 20 2017 13:59:33 %S A007200 12,48,180,792,3444,15000,64932,280200,1204572,5159448,22043292, %T A007200 93952428,399711348,1697721852,7200873444,30500477676,129049335924, %U A007200 545436439536,2303305856916 %N A007200 Number of self-avoiding walks on hexagonal lattice, with additional constraints. %C A007200 The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice. %C A007200 The extra constraint here is that the next to "middle" points of the walk must be adjacent in the lattice. Exact details are in the Redner paper. - _Sean A. Irvine_, Nov 20 2017 %D A007200 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A007200 G. Nebe and N. J. A. Sloane, <a href="http://www.math.rwth-aachen.de/~Gabriele.Nebe/LATTICES/A2.html">Home page for hexagonal (or triangular) lattice A2</a> %H A007200 S. Redner, <a href="http://physics.bu.edu/~redner/pubs/pdf/jpa13p3525.pdf">Distribution functions in the interior of polymer chains</a>, J. Phys. A 13 (1980), 3525-3541, doi:10.1088/0305-4470/13/11/023. %Y A007200 Cf. A007201. %K A007200 nonn,walk %O A007200 2,1 %A A007200 _Simon Plouffe_ %E A007200 a(15)-a(20) from _Sean A. Irvine_, Nov 20 2017