a(1) = 3 because the first 3 digits of the base e expansion of Pi are 10.1 [meaning pi ~ 1*(e^1) + 0*(e^0) + 1*(e^1)] and 101 (base 10) is prime.
a(2) = 18 because the first 18 digits of the base e expansion of Pi are 1, 0, 1010020200021111 which (base 10) is prime.
a(3) = 84 because there are 84 digits in 101010020200021111200201011200010102020001110120200101200020011011201012100100021001 which is prime.
