Number of subsets of the set {1,2,...,n} which do not contain two elements whose difference is 6.

Terms

a(0) =2a(1) =4a(2) =8a(3) =16a(4) =32a(5) =64a(6) =96a(7) =144a(8) =216a(9) =324a(10) =486a(11) =729a(12) =1215a(13) =2025a(14) =3375a(15) =5625a(16) =9375a(17) =15625a(18) =25000a(19) =40000a(20) =64000a(21) =102400a(22) =163840a(23) =262144a(24) =425984a(25) =692224a(26) =1124864a(27) =1827904a(28) =2970344a(29) =4826809