a(n) = [ n/{n*sqrt(7)} ], where {x} := x - [ x ].

Terms

a(0) =1a(1) =6a(2) =3a(3) =6a(4) =21a(5) =6a(6) =13a(7) =48a(8) =11a(9) =21a(10) =106a(11) =16a(12) =32a(13) =345a(14) =21a(15) =48a(16) =17a(17) =28a(18) =70a(19) =21a(20) =37a(21) =106a(22) =26a(23) =48a(24) =173a(25) =32a(26) =62a(27) =345a(28) =39a(29) =80