Duplicate of A000337.

Terms

a(0) =0a(1) =1a(2) =5a(3) =17a(4) =49a(5) =129a(6) =321a(7) =769a(8) =1793a(9) =4097a(10) =9217a(11) =20481a(12) =45057a(13) =98305a(14) =212993