Number of subsets of {1,2,...,n} such that no two elements differ by 1 or 5.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =8a(5) =13a(6) =18a(7) =28a(8) =41a(9) =62a(10) =91a(11) =141a(12) =208a(13) =317a(14) =473a(15) =719a(16) =1069a(17) =1623a(18) =2425a(19) =3666a(20) =5487a(21) =8295a(22) =12424a(23) =18751a(24) =28130a(25) =42416a(26) =63657a(27) =95944a(28) =144083a(29) =217023