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 A321351 #16 Dec 08 2018 17:50:03 %S A321351 0,1,0,26,3,0,19,5,0,21,7,0,23,9,0,25,11,0,27,13,0,29,15,0,2,17,0,4, %T A321351 19,0,6,21,0,8,23,0,10,25,0,12,27,0,14,29,0,16,31,0,18,33,0,20,35,0,22 %N A321351 a(n) is the index of the row of A321350 in which n first appears, or zero if n does not appear. %C A321351 No multiple of 3 appears, so a(3n) = 0 for all n. %F A321351 a(n) <= (2/3)*n + 15 for n > 6. %e A321351 a(5) = 3, since in A321350, 2 --> (2+3)^2 --> 5, so 5 first appears in the third row. %Y A321351 Cf. A296142, A321350. %K A321351 nonn,hard %O A321351 1,4 %A A321351 _Jeremy F. Alm_, Nov 06 2018