Number of subsets of {1,2,...,n} such that no two elements differ by 1, 2, 4, or 5.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =6a(5) =8a(6) =10a(7) =14a(8) =19a(9) =25a(10) =35a(11) =48a(12) =64a(13) =88a(14) =120a(15) =161a(16) =220a(17) =300a(18) =405a(19) =552a(20) =752a(21) =1018a(22) =1385a(23) =1885a(24) =2556a(25) =3475a(26) =4727a(27) =6416a(28) =8720a(29) =11857