a(n) is the number of smallest parts in the overpartitions of n having odd smallest part.

Terms

a(0) =2a(1) =4a(2) =12a(3) =20a(4) =40a(5) =72a(6) =124a(7) =200a(8) =330a(9) =520a(10) =804a(11) =1224a(12) =1832a(13) =2704a(14) =3960a(15) =5704a(16) =8144a(17) =11532a(18) =16164a(19) =22480a(20) =31056a(21) =42568a(22) =57972a(23) =78480a(24) =105610a(25) =141336a(26) =188208a(27) =249352a(28) =328824a(29) =431760