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

Terms

a(0) =5a(1) =4a(2) =9a(3) =5a(4) =20a(5) =9a(6) =29a(7) =18a(8) =40a(9) =61a(10) =52a(11) =77a(12) =121a(13) =85a(14) =235a(15) =165a(16) =281a(17) =393a(18) =438a(19) =586a(20) =645a(21) =884a(22) =1997a(23) =777a(24) =1597a(25) =3598a(26) =4901a(27) =4442a(28) =8249a(29) =4582