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 A343643 #16 May 27 2021 16:15:36 %S A343643 0,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,-1,-1,-1,-1,-1,-1,-1,-1,-1,-2,-2, %T A343643 -2,-2,-2,-2,-2,-2,-2,-2,-2,-2,-2,-2,-2,-2,-2,-2,-2,-2,-2,-2,-2,-2,-2, %U A343643 -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2 %N A343643 Z-coordinate of points following the 3D square spiral defined in A343640. %C A343643 See A343640 for more information about this 3D generalization of the 2D Ulam type square spiral. %C A343643 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. %C A343643 The graph of this sequence oscillates with increasing amplitude and wave length. %H A343643 Hugo Pfoertner, <a href="/A343643/b343643.txt">Table of n, a(n) for n = 0..9260</a> %o A343643 (PARI) A343643_vec=concat([[P[3]| P<-A343640_row(n)] | n<-[0..2]]) \\ From 0 up to n there are (2n+1)^3 points with 3 coordinates each. %Y A343643 Cf. A343640 (triples), A343641 and A343642 (list of X and Y-coordinates). %Y A343643 Cf. A343633 (variant using the Euclidean norm), A342563 (another variant). %Y A343643 Cf. A010014 (number of points on a shell with given radius => row lengths). %K A343643 sign,tabf %O A343643 0,28 %A A343643 _M. F. Hasler_, Apr 28 2021