Sum of CarmichaelLambda[n] between successive powers of 2.

Terms

a(0) =1a(1) =3a(2) =14a(3) =46a(4) =206a(5) =694a(6) =2610a(7) =9420a(8) =35038a(9) =130784a(10) =484136a(11) =1827996a(12) =6891816a(13) =26121822a(14) =99232238a(15) =379021972a(16) =1450654796a(17) =5564804616a(18) =21406426134a(19) =82457456808