Second-order Eulerian numbers <<n,2>>.

Terms

a(0) =0a(1) =6a(2) =58a(3) =328a(4) =1452a(5) =5610a(6) =19950a(7) =67260a(8) =218848a(9) =695038a(10) =2170626a(11) =6699696a(12) =20507988a(13) =62407890a(14) =189123286a(15) =571432036a(16) =1722945672a(17) =5187185766a(18) =15600353130a(19) =46882846680a(20) =140820504700a(21) =422822222266