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 A308180 #13 May 31 2019 10:33:21 %S A308180 0,3,5,2,1,6,7,11,4,12,18,14,13,8,17,9,22,23,25,29,10,28,19,30,38,31, %T A308180 39,15,47,24,16,40,34,42,50,51,41,44,46,49,58,55,45,21,66,69,20,56,65, %U A308180 60,73,67,77,57,78,63,79,70,26,27,85,87,93,76,82,89,71 %N A308180 Main diagonal of triangle defined in A308178. %C A308180 Theorem: This is a permutation of the nonnegative integers. [The proof is analogous to that for A286295.] %C A308180 Conjecture: There is a unique fixed point at n=0, and the positive integers form one "cycle", namely (... 59 27 15 9 12 13 8 4 1 3 2 5 6 7 11 14 17 23 30 16 22 19 29 24 38 ...). %H A308180 Rémy Sigrist, <a href="/A308180/b308180.txt">Table of n, a(n) for n = 0..5000</a> %Y A308180 Cf. A308178, A308179, A286295. %K A308180 nonn %O A308180 0,2 %A A308180 _N. J. A. Sloane_, May 28 2019 %E A308180 More terms from _Rémy Sigrist_, May 29 2019