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

Terms

a(0) =0a(1) =2a(2) =5a(3) =14a(4) =44a(5) =165a(6) =725a(7) =3607a(8) =19624a(9) =115127a(10) =716177a(11) =4675144a(12) =31743253a(13) =222710685a(14) =1606581461a(15) =11868655658a(16) =89506275569a(17) =687275710608