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) =1a(10) =11a(11) =22a(12) =78a(13) =299a(14) =1015a(15) =3018a(16) =8024a(17) =19465a(18) =43776a(19) =92397a(20) =191a(21) =231a(22) =462a(23) =2024a(24) =10902a(25) =53430a(26) =230555a(27) =888381a(28) =3108483a(29) =10015411