Exponential convolution of primes with themselves.

Terms

a(0) =4a(1) =12a(2) =38a(3) =118a(4) =362a(5) =1082a(6) =3166a(7) =8910a(8) =24426a(9) =64226a(10) =165262a(11) =413418a(12) =1021362a(13) =2490686a(14) =6009150a(15) =14401410a(16) =34098042a(17) =80281962a(18) =187356750a(19) =432549154a(20) =992941250a(21) =2256712462a(22) =5088826238a(23) =11408805862a(24) =25425739346a(25) =56383362854a(26) =124565557898a(27) =274390550594