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 A326989 #15 Aug 24 2019 21:31:06 %S A326989 0,0,3,0,5,3,6,7,0,3,9,5,10,11,3,6,12,13,7,14,3,5,15,0,17,3,6,9,18,19, %T A326989 5,10,20,3,7,21,11,22,23,3,6,12,24,5,25,13,26,3,9,27,7,14,28,29,3,5,6, %U A326989 10,15,30,31,0,3,11,33,17,34,5,7,35,3,6,9,12,18,36,37,19,38,3,13,39,5,10,20,40,41 %N A326989 Triangle read by rows in which row n lists the nonpowers of 2 dividing n, or 0 if n is a power of 2. %C A326989 Row n has length A326987(n) if n is not a power of 2, otherwise row n has length 1. %e A326989 Triangle begins: %e A326989 0; %e A326989 0; %e A326989 3; %e A326989 0; %e A326989 5; %e A326989 3, 6; %e A326989 7; %e A326989 0; %e A326989 3, 9; %e A326989 5, 10; %e A326989 11; %e A326989 3, 6, 12; %e A326989 13; %e A326989 7, 14; %e A326989 3, 5, 15; %e A326989 0; %e A326989 17; %e A326989 3, 6, 9, 18; %e A326989 ... %e A326989 For n = 18 the divisors of 18 are [1, 2, 3, 6, 9, 18]. There are four divisors of 18 that are not powers of 2, they are [3, 6, 9, 18], the same as the 18th row of triangle. %Y A326989 Row sums give A326988. %Y A326989 Cf. A000079, A027750, A057716, A326987. %K A326989 nonn,tabf,easy %O A326989 1,3 %A A326989 _Omar E. Pol_, Aug 24 2019