a(n) is the total number of elements in all sum-free subsets of {1,...,n}.

Terms

a(0) =1a(1) =2a(2) =7a(3) =12a(4) =27a(5) =45a(6) =93a(7) =144a(8) =294a(9) =428a(10) =796a(11) =1220a(12) =2186a(13) =3155a(14) =5637a(15) =8102a(16) =13907a(17) =20070a(18) =33746a(19) =47416a(20) =81050a(21) =112226a(22) =184541a(23) =260780a(24) =421222a(25) =577447a(26) =947934a(27) =1304821a(28) =2087701a(29) =2857024