201801600

Appears in sequences

• Denominator of Sum_{i+j+k=n; i,j,k > 0} 1/(i*j*k).at n=15A002546
• Unitary superperfect numbers: numbers n such that usigma(usigma(n)) = 2*n, where usigma(n) is the sum of unitary divisors of n (A034448).at n=25A038843
• Product of related numbers (counted in A073757) belonging to n; related = {divisor-set, RRS}: a(n) = A007955(n)*A001783(n).at n=14A083267
• Denominator of 3*Sum_{i=1..n} 1/(i^2*C(2*i,i)).at n=8A112094
• Number T(n,k) of 2n-length strings of balanced parentheses of exactly k different types; triangle T(n,k), n>=0, 0<=k<=n, read by rows.at n=43A256061