Number of Carmichael numbers (A002997) less than 2^n.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =0a(8) =0a(9) =1a(10) =3a(11) =5a(12) =6a(13) =9a(14) =10a(15) =15a(16) =19a(17) =23a(18) =33a(19) =45a(20) =55a(21) =69a(22) =95a(23) =130a(24) =162a(25) =214a(26) =290a(27) =375a(28) =483a(29) =656