a(n) = ceiling(Pi^n).

Terms

a(0) =1a(1) =4a(2) =10a(3) =32a(4) =98a(5) =307a(6) =962a(7) =3021a(8) =9489a(9) =29810a(10) =93649a(11) =294205a(12) =924270a(13) =2903678a(14) =9122172a(15) =28658146a(16) =90032221a(17) =282844564a(18) =888582404a(19) =2791563950a(20) =8769956797a(21) =27551631843a(22) =86556004192a(23) =271923706894a(24) =854273519914