Number of odd nonprimes <= (2n+1)^2.

Terms

a(0) =1a(1) =2a(2) =5a(3) =11a(4) =20a(5) =32a(6) =47a(7) =66a(8) =85a(9) =110a(10) =137a(11) =167a(12) =200a(13) =237a(14) =276a(15) =320a(16) =365a(17) =414a(18) =467a(19) =522a(20) =579a(21) =643a(22) =708a(23) =777a(24) =845a(25) =924a(26) =997a(27) =1080a(28) =1169a(29) =1255