a(n) = floor(a(n-1)*(Pi-1)); a(1) = 1.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =17a(5) =36a(6) =77a(7) =164a(8) =351a(9) =751a(10) =1608a(11) =3443a(12) =7373a(13) =15789a(14) =33813a(15) =72413a(16) =155079a(17) =332116a(18) =711257a(19) =1523222a(20) =3262121a(21) =6986134a(22) =14961453a(23) =32041337a(24) =68619491a(25) =146954997a(26) =314717741a(27) =673997202a(28) =1443427456a(29) =3091233635