a(0)=a(1)=1; a(n) = lcm(a(n-1) + a(n-2), n).

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =20a(5) =115a(6) =270a(7) =385a(8) =5240a(9) =5625a(10) =21730a(11) =300905a(12) =1290540a(13) =20688785a(14) =307710550a(15) =328399335a(16) =10177758160a(17) =178604677415a(18) =377564871150