(Prime(prime(n))^2+1)/2.

Terms

a(0) =5a(1) =13a(2) =61a(3) =145a(4) =481a(5) =841a(6) =1741a(7) =2245a(8) =3445a(9) =5941a(10) =8065a(11) =12325a(12) =16021a(13) =18241a(14) =22261a(15) =29041a(16) =38365a(17) =40045a(18) =54781a(19) =62305a(20) =67345a(21) =80401a(22) =92881a(23) =106261a(24) =129541a(25) =149605a(26) =158485a(27) =172285a(28) =179401a(29) =190345