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 A358083 #13 Nov 02 2022 07:15:42 %S A358083 4,16,128,448,2256,5376,29424,69888,302568,741376,3026448,7216896, %T A358083 29268352,65785216,263892736,591065568,2279452040,5195776064, %U A358083 19324558176,44442289024,161417689504,371206519136,1328055630144,3044451252064,10774811055304,24625495784320,86363375773808,197092099990080 %N A358083 Sum of square end-to-end displacements over all n-step self-avoiding walks of A358046. %C A358083 See A358046 for further details. %e A358083 a(3) = 128 as, in the first quadrant, the four 3-step SAWs that have the first and last visited lattice point being mutually visible are: %e A358083 . %e A358083 X %e A358083 | %e A358083 X---. . .---X X %e A358083 | | | | %e A358083 X---. X---. X---. X---.---. %e A358083 . %e A358083 The sum of square end-to-end displacements of these four walks is 1 + 5 + 5 + 5 = 16. They can be walked in eight different ways on a square lattice thus a(3) = 16 * 8 = 128. %Y A358083 Cf. A358046, A358084, A001411, A336448. %K A358083 nonn,walk %O A358083 1,1 %A A358083 _Scott R. Shannon_, Oct 30 2022