a(n) is the smallest n-gonal number with binary weight n.

Terms

a(0) =21a(1) =169a(2) =117a(3) =190a(4) =1404a(5) =9976a(6) =3961a(7) =11935a(8) =19966a(9) =113401a(10) =98155a(11) =208879a(12) =261501a(13) =3338221a(14) =916475a(15) =3100671a(16) =9943039a(17) =31457140a(18) =50322871a(19) =100523871a(20) =264240373a(21) =2113871829a(22) =2012739435a(23) =532673535a(24) =7415513007a(25) =33017544153a(26) =17112759966a(27) =50983861215a(28) =59039022015