a(n) = floor(sqrt(n)) * a(n-1), starting with 1.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =4a(5) =8a(6) =16a(7) =32a(8) =96a(9) =288a(10) =864a(11) =2592a(12) =7776a(13) =23328a(14) =69984a(15) =279936a(16) =1119744a(17) =4478976a(18) =17915904a(19) =71663616a(20) =286654464a(21) =1146617856a(22) =4586471424a(23) =18345885696a(24) =91729428480a(25) =458647142400