Number of subsets of {1..n} whose cardinality is equal to the sum of some subset.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =10a(5) =20a(6) =40a(7) =82a(8) =169a(9) =348a(10) =716a(11) =1471a(12) =3016a(13) =6171a(14) =12605a(15) =25710a(16) =52370a(17) =106539a(18) =216470a(19) =439310a(20) =890550a(21) =1803415a(22) =3648557a(23) =7375141a(24) =14896184a(25) =30065129a(26) =60639954a(27) =122231740a(28) =246239551a(29) =495790161