Number of three-prime Carmichael numbers less than 10^n.

Terms

a(0) =1a(1) =7a(2) =12a(3) =23a(4) =47a(5) =84a(6) =172a(7) =335a(8) =590a(9) =1000a(10) =1858a(11) =3284a(12) =6083a(13) =10816a(14) =19539a(15) =35586a(16) =65309a(17) =120625a(18) =224763a(19) =420658a(20) =790885a(21) =1494738