70862domain: NAppears in sequencesa(n) = floor( n*(n-1)*(n-2)*(n-3)/25 ).at n=38A011935Number of unordered pairs of partitions of n with no common parts.at n=23A260669Expansion of Sum_{k>=1} k * x^k / (1 - k * x^k)^k.at n=20A324159a(n) = - Sum_{d|n} (-n/d)^d * binomial(d+n/d-2, d-1).at n=20A338688