925166131890domain: NAppears in sequencesNumber of partitions of { 1, 2, ..., 10n } into sets of size 10.at n=3A025042a(n) = (1/6)*multinomial(3*n;n,n,n).at n=9A060542a(n) = Sum_{k = 0..n-1} (-1)^k*binomial(n,k)*binomial(n-1,k)^2.at n=20A361710