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 A338509 #12 Nov 01 2020 04:11:57 %S A338509 0,0,0,0,1,5,4,23,12,10,36,62,87,20,120,130,289,35,284,432,235,200, %T A338509 356,682,56,555,1256,385,1005,795,1330,84,960,2775,588,2939,1501,1844, %U A338509 2297,120,3436,1526,4304,1720,5205,852,6514,2538,5001,3647,165,7341,2280,2280,11712 %N A338509 a(n) is the number of ordered triples of divisors d_i < d_j < d_k of m such that GCD(d_i, d_j, d_k) > 1 where m is the least number having its prime signature; m = A025487(n). %C A338509 Primitive sequence to A336530 as that sequence only depends on the prime signature of n. %H A338509 David A. Corneth, <a href="/A338509/b338509.txt">Table of n, a(n) for n = 1..10000</a> %F A338509 a(n) = A336530(A025487(n)). %e A338509 a(6) = 12 as A025487(6) = 12 and there are 5 triples of divisors of 12 (x, y, z) such that g = gcd(x, y, z) are 12. 4 of them have g = 2 as 12/2 = 6 has 4 divisors and binomial(4, 3) = 4, 1 of them has g = 3 as 12/3 = 4 has 3 divisors and binomial(3, 3) = 1 and 0 of them have g = 6 as 12/6 = 2 has 3 divisors and binomial(2, 3) = 0. %Y A338509 Cf. A025487, A336530. %K A338509 nonn,easy %O A338509 1,6 %A A338509 _David A. Corneth_, Oct 31 2020