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 A174063 #13 Sep 26 2020 11:42:55 %S A174063 1,2,3,2,3,5,2,3,5,7,4,5,6,7,9,4,5,6,7,9,11,4,5,6,7,9,11,13,4,6,7,9, %T A174063 10,11,13,15,4,6,7,9,10,11,13,15,17,4,6,7,9,10,11,13,15,17,19,4,6,9, %U A174063 10,11,13,14,15,17,19,21,4,6,9,10,11,13,14,15,17,19,21,23,4,6,9,10,11,13,14 %N A174063 Triangular array (read by rows) containing the least n integers < 2n such that no integer divides another. %C A174063 The first number on each row is 2^k, where k is the greatest integer such that (3^k)/2 < n. %e A174063 1; %e A174063 2, 3; %e A174063 2, 3, 5; %e A174063 2, 3, 5, 7; %e A174063 4, 5, 6, 7, 9; %e A174063 4, 5, 6, 7, 9, 11; %e A174063 4, 5, 6, 7, 9, 11, 13; %e A174063 4, 6, 7, 9, 10, 11, 13, 15; %t A174063 noneDivQ[L_] := NoneTrue[Subsets[L, {2}], Divisible[#[[2]], #[[1]]]&]; %t A174063 k1[n_] := For[k = Log[3, 2n]//Ceiling, True, k--, If[(3^k)/2<n, Return[k]]]; %t A174063 row[n_] := SelectFirst[Subsets[Range[2^k1[n], 2n-1], {n}], noneDivQ]; %t A174063 Array[row, 13] // Flatten (* _Jean-François Alcover_, Sep 25 2020 *) %Y A174063 Cf. A174062, A174094. %K A174063 nonn,tabl %O A174063 1,2 %A A174063 _David Brown_, Mar 07 2010 %E A174063 Definition corrected by _David Brown_, Mar 20 2010