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 A324480 #19 Dec 05 2021 06:49:03 %S A324480 0,1,1,2,2,3,4,3,7,6,4,5,8,10,5,6,7,11,8,12,14,10,18,9,9,13,12,20,21, %T A324480 24,11,22,13,14,16,17,15,15,17,18,19,36,16,23,26,23,21,27,19,27,28,20, %U A324480 22,25,24,43,29,47,50,25,26,37,43,49,34,28,42,52,53,30,30 %N A324480 Consider the numbers on the x-axis in the spiral shown in A274641; a(n) is the distance from n to the origin, or -1 if n never appears on the x-axis. %C A324480 It is conjectured that every nonnegative number appears on the x-axis exactly once. %C A324480 a(n) is also the distance to the origin from the point n+1 on the x-axis in A274640. %H A324480 Rémy Sigrist, <a href="/A324480/b324480.txt">Table of n, a(n) for n = 0..4999</a> %H A324480 Rémy Sigrist, <a href="/A324480/a324480.gp.txt">PARI program for A324480</a> %e A324480 The portion of the x-axis near 0 is: %e A324480 ... 14 6 5 4 2 0 1 3 7 10 11 ... %e A324480 and we see that both 1 and 2 are at distance 1 from 0. So a(1) = a(2) = 1. %o A324480 (PARI) See Links section. %Y A324480 Cf. A274640, A274641. %Y A324480 The positive and negative x-axes are given in A274924 and A274928. %K A324480 nonn %O A324480 0,4 %A A324480 _N. J. A. Sloane_, Mar 11 2019 %E A324480 More terms from _Jinyuan Wang_, Feb 27 2020