Number of combinations of n objects taken pi(n) at a time.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =6a(5) =10a(6) =20a(7) =35a(8) =70a(9) =126a(10) =210a(11) =462a(12) =792a(13) =1716a(14) =3003a(15) =5005a(16) =8008a(17) =19448a(18) =31824a(19) =75582a(20) =125970a(21) =203490a(22) =319770a(23) =817190a(24) =1307504a(25) =2042975a(26) =3124550a(27) =4686825a(28) =6906900a(29) =20030010