Numbers formed by the third nesting of pi(10^n).

Terms

a(0) =1a(1) =4a(2) =12a(3) =46a(4) =194a(5) =977a(6) =5492a(7) =33666a(8) =220068a(9) =1513371a(10) =10833076a(11) =80104927a(12) =608455060a(13) =4726881850a(14) =37431015268a(15) =301327263751