Number of nonempty subsets of {1..n} whose elements have an odd average.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =9a(5) =13a(6) =20a(7) =38a(8) =71a(9) =119a(10) =206a(11) =384a(12) =713a(13) =1285a(14) =2356a(15) =4428a(16) =8331a(17) =15569a(18) =29270a(19) =55582a(20) =105717a(21) =200847a(22) =382808a(23) =732744a(24) =1404667a(25) =2694391a(26) =5178186a(27) =9973416a(28) =19233457a(29) =37125547