Smallest positive number containing n e's when spelled out in US English.

Terms

a(0) =2a(1) =1a(2) =3a(3) =11a(4) =17a(5) =111a(6) =117a(7) =317a(8) =1317a(9) =3317a(10) =11317a(11) =17317a(12) =111317a(13) =117317a(14) =317317a(15) =1317317a(16) =3317317a(17) =11317317a(18) =17317317a(19) =111317317a(20) =117317317a(21) =317317317a(22) =1317317317a(23) =3317317317a(24) =11317317317a(25) =17317317317a(26) =111317317317a(27) =117317317317a(28) =317317317317