The triangular sequence of symmetrical Lah numbers (A111596, A008297) : L(n, m) = (-1)^n* binomial(n,k)*binomial(n-1, k-1)*( (n-k)! + (n-k)*(k-1)! ), with L(0,0) = 2, L(n,0) = L(n,n) = (-1)^n.

A156786

The triangular sequence of symmetrical Lah numbers (A111596, A008297) : L(n, m) = (-1)^n* binomial(n,k)*binomial(n-1, k-1)*( (n-k)! + (n-k)*(k-1)! ), with L(0,0) = 2, L(n,0) = L(n,n) = (-1)^n.

Terms

    a(0) =2a(1) =-1a(2) =-1a(3) =1a(4) =4a(5) =1a(6) =-1a(7) =-12a(8) =-12a(9) =-1a(10) =1a(11) =36a(12) =72a(13) =36a(14) =1a(15) =-1a(16) =-140a(17) =-360a(18) =-360a(19) =-140a(20) =-1a(21) =1a(22) =750a(23) =2100a(24) =2400a(25) =2100a(26) =750a(27) =1a(28) =-1a(29) =-5082

External references