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

Terms

a(0) =0a(1) =1a(2) =4a(3) =10a(4) =19a(5) =31a(6) =46a(7) =65a(8) =84a(9) =109a(10) =136a(11) =166a(12) =199a(13) =236a(14) =275a(15) =319a(16) =364a(17) =413a(18) =466a(19) =521a(20) =578a(21) =642a(22) =707a(23) =776a(24) =844a(25) =923a(26) =996a(27) =1079a(28) =1168a(29) =1254