Table read by rows. A statistic of permutations of the multiset {1,1,2,2,...,n,n}.

Terms

a(0) =1a(1) =5a(2) =1a(3) =47a(4) =42a(5) =1a(6) =641a(7) =1659a(8) =219a(9) =1a(10) =11389a(11) =72572a(12) =28470a(13) =968a(14) =1a(15) =248749a(16) =3610485a(17) =3263402a(18) =357746a(19) =4017a(20) =1a(21) =6439075a(22) =204023334a(23) =371188155a(24) =95559940a(25) =3853617a(26) =16278a(27) =1a(28) =192621953a(29) =12989570167