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

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =6a(5) =9a(6) =12a(7) =17a(8) =25a(9) =35a(10) =49a(11) =71a(12) =101a(13) =142a(14) =203a(15) =290a(16) =410a(17) =583a(18) =832a(19) =1181a(20) =1677a(21) =2389a(22) =3397a(23) =4825a(24) =6865a(25) =9766a(26) =13879a(27) =19736a(28) =28074a(29) =39913