a(n) is the number of subsets of {1..n} that contain exactly 4 odd and 1 even numbers.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =3a(8) =4a(9) =20a(10) =25a(11) =75a(12) =90a(13) =210a(14) =245a(15) =490a(16) =560a(17) =1008a(18) =1134a(19) =1890a(20) =2100a(21) =3300a(22) =3630a(23) =5445a(24) =5940a(25) =8580a(26) =9295a(27) =13013a(28) =14014a(29) =19110