a(n) = lcm(1,...,n) - (product of primes <= n).

Terms

a(0) =0a(1) =0a(2) =0a(3) =6a(4) =30a(5) =30a(6) =210a(7) =630a(8) =2310a(9) =2310a(10) =25410a(11) =25410a(12) =330330a(13) =330330a(14) =330330a(15) =690690a(16) =11741730a(17) =11741730a(18) =223092870a(19) =223092870a(20) =223092870a(21) =223092870a(22) =5131136010a(23) =5131136010a(24) =26548051530a(25) =26548051530a(26) =80090340330a(27) =80090340330