a(n) = least semiprime such that all subsets of {a(1),...,a(n)} have a different sum.

Terms

a(0) =4a(1) =6a(2) =9a(3) =14a(4) =22a(5) =57a(6) =111a(7) =218a(8) =445a(9) =879a(10) =1754a(11) =3518a(12) =7034a(13) =14069a(14) =28129a(15) =56271a(16) =112529a(17) =225073a(18) =450139a(19) =900274a(20) =1800559a(21) =3601109a(22) =7202221a(23) =14404439a(24) =28808881a(25) =57617759a(26) =115235531a(27) =230471069a(28) =460942121