cp's OEIS Frontend

A096180 Triangle read by rows: fraction of integers having k of the first n positive integers as divisors is T(n,k)/A003418(n).

%I A096180 #12 Feb 19 2019 04:42:08
%S A096180 1,1,1,2,3,1,4,4,3,1,16,20,16,7,1,16,20,12,6,5,1,96,136,92,48,36,11,1,
%T A096180 192,272,136,124,66,38,11,1,576,720,464,360,206,122,58,13,1,576,720,
%U A096180 392,384,188,154,70,26,9,1,5760,7776,4640,4232,2264,1728,854,330,116,19
%N A096180 Triangle read by rows: fraction of integers having k of the first n positive integers as divisors is T(n,k)/A003418(n).
%C A096180 Sum of entries in n-th row is A003418(n), the least common multiple of integers 1 to n.
%e A096180 Triangle begins:
%e A096180 1
%e A096180 1 1
%e A096180 2 3 1
%e A096180 4 4 3 1
%e A096180 16 20 16 7 1
%e A096180 16 20 12 6 5 1
%o A096180 (PARI) lcmn(n) = lcm(vector(n, k, k));
%o A096180 rowd(n) = {v = vector(n); for (k=1, lcmn(n), d = divisors(k); v[sum(j=1, #d, d[j]<=n)]++;); v;} \\ _Michel Marcus_, Apr 29 2017
%Y A096180 Cf. A003418, A217863 (first column).
%K A096180 nonn,tabl
%O A096180 1,4
%A A096180 _Matthew Vandermast_, Jun 19 2004