a(n) = floor(x(n)) where x(n) = (frac(x(n-1))+1)*floor(x(n-1)) and x(1) = Pi.

Terms

a(0) =3a(1) =3a(2) =4a(3) =5a(4) =5a(5) =7a(6) =10a(7) =10a(8) =13a(9) =17a(10) =31a(11) =35a(12) =67a(13) =123a(14) =223a(15) =305a(16) =414a(17) =822a(18) =1550a(19) =2224a(20) =3273a(21) =4560a(22) =7804a(23) =14372a(24) =15493a(25) =20080a(26) =40039a(27) =44226a(28) =71916a(29) =130773