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 A328459 #16 Mar 31 2023 14:10:18 %S A328459 1,2,6,12,60,420,504,840,2520,27720,360360,720720,4084080 %N A328459 Sorted positions of first appearances in A328458 (maximum run-length of nontrivial divisors) of each positive integer in the image. %e A328459 The sequence of terms > 1 together with their nontrivial divisors begins: %e A328459 2: {} %e A328459 6: {2,3} %e A328459 12: {2,3,4,6} %e A328459 60: {2,3,4,5,6,10,12,15,20,30} %e A328459 420: {2,3,4,5,6,7,10,12,14,15,20,21,28,30,35,42,60,70,84,105,140,210} %e A328459 504: {2,3,4,6,7,8,9,12,14,18,21,24,28,36,42,56,63,72,84,126,168,252} %t A328459 dav=Table[Switch[n,1,1,_,Max@@Length/@Split[DeleteCases[Divisors[n],1|n],#2==#1+1&]],{n,1000}]; %t A328459 Table[Position[dav,i][[1,1]],{i,Union[dav]}]//Sort %Y A328459 Positions of first appearances in A328458. %Y A328459 The version for all divisors is A051451. %Y A328459 Cf. A000005, A033676, A060775, A070824, A119313, A129308, A181063, A199970, A163870, A328448, A328449. %K A328459 nonn,more %O A328459 0,2 %A A328459 _Gus Wiseman_, Oct 17 2019 %E A328459 a(12) from _Robert Israel_, Mar 31 2023