a(n) = floor((Sum_{i=1..n} 1/i)^n).

Terms

a(0) =1a(1) =2a(2) =6a(3) =18a(4) =62a(5) =216a(6) =787a(7) =2977a(8) =11605a(9) =46467a(10) =190494a(11) =797508a(12) =3402436a(13) =14766894a(14) =65102146a(15) =291182808a(16) =1319875827a(17) =6057465890a(18) =28124389866a(19) =132006302556a(20) =625958670808