a(n) = C(n,a)*C(n,b)*C(n,c)... where n = abc... are the decimal digits of n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =1a(7) =1a(8) =1a(9) =10a(10) =121a(11) =792a(12) =3718a(13) =14014a(14) =45045a(15) =128128a(16) =330616a(17) =787644a(18) =1755182a(19) =190a(20) =4410a(21) =53361a(22) =448063a(23) =2932776a(24) =15939000a(25) =74824750a(26) =311698530a(27) =1174863690a(28) =4066092030a(29) =4060