a(n) = n! * Sum_{k=1..n} 1/(k! * floor(n/k)).

Terms

a(0) =1a(1) =2a(2) =6a(3) =17a(4) =80a(5) =337a(6) =2240a(7) =14681a(8) =117010a(9) =1023941a(10) =10900472a(11) =108881665a(12) =1375544846a(13) =17732140805a(14) =247041590476