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 A259802 #17 Sep 30 2021 18:14:30
%S A259802 2,12,50,188,652,2140,6766,20868,63118,188004,553074,1610776,4651784,
%T A259802 13338744,38014494,107767964,304100432,854624852,2393093804,
%U A259802 6679440288,18589013256,51597951784,142880148016,394791197276,1088674291748,2996639940048
%N A259802 Guttmann-Torrie series coefficients rho_n*c_{n}^{2} for square lattice, with wedge angle Pi/2.
%C A259802 The sum of squared end-to-end distances of all n-step self-avoiding walks on a 2D square lattice confined to one quadrant of the grid. - _Scott R. Shannon_, Sep 27 2021
%H A259802 A. J. Guttmann and G. M. Torrie, <a href="https://doi.org/10.1088/0305-4470/17/18/023">Critical behavior at an edge for the SAW and Ising model</a>, J. Phys. A 17 (1984), 3539-3552.
%Y A259802 Cf. A038373 (number of SAWs in quadrant grid).
%K A259802 nonn
%O A259802 1,1
%A A259802 _N. J. A. Sloane_, Jul 06 2015
%E A259802 a(23)-a(26) from _Scott R. Shannon_, Sep 27 2021