Triangle T(n,k) of rencontres numbers (number of permutations of n elements with k fixed points).

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =0a(5) =1a(6) =2a(7) =3a(8) =0a(9) =1a(10) =9a(11) =8a(12) =6a(13) =0a(14) =1a(15) =44a(16) =45a(17) =20a(18) =10a(19) =0a(20) =1a(21) =265a(22) =264a(23) =135a(24) =40a(25) =15a(26) =0a(27) =1a(28) =1854a(29) =1855