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 A343642 #8 May 06 2021 22:09:13 %S A343642 0,0,0,1,1,1,0,-1,-1,-1,0,1,1,1,0,-1,-1,-1,0,1,1,1,0,-1,-1,-1,0,0,0,1, %T A343642 1,1,0,-1,-1,-1,0,1,2,2,2,2,2,1,0,-1,-2,-2,-2,-2,-2,-1,0,1,2,2,2,2,2, %U A343642 1,0,-1,-2,-2,-2,-2,-2,-1,0,1,2,2,2,2,2,1,0,-1,-2,-2,-2,-2,-2,-1,0,1,2,2,2,2,2,1,0,-1,-2,-2,-2,-2,-2,-1,0,1,2,2,2,2,2,1,0 %N A343642 Y-coordinate of points following the 3D square spiral defined in A343640. %C A343642 See A343640 for more information about this 3D generalization of the 2D Ulam type square spiral. %C A343642 The sequence can be seen as a table with row lengths A010014, where A010014(r) is the number of points of Z^3 with sup-norm r. %H A343642 Hugo Pfoertner, <a href="/A343642/b343642.txt">Table of n, a(n) for n = 0..9260</a> %o A343642 (PARI) A343642_vec=concat([[P[2]| P<-A343640_row(n)] | n<-[0..2]]) \\ From 0 up to n there are (2n+1)^3 points with 3 coordinates each. %Y A343642 Cf. A343641, A343643 (list of x and z-coordinates). %Y A343642 Cf. A343632 (variant using the Euclidean norm), A342562 (another variant). %Y A343642 Cf. A010014 (number of points on a shell with given radius => row lengths). %K A343642 sign,look,tabf %O A343642 0,39 %A A343642 _M. F. Hasler_, Apr 28 2021