Number of subsets of the set {1,2,...,n} which do not contain two elements whose difference is 5.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =16a(5) =32a(6) =48a(7) =72a(8) =108a(9) =162a(10) =243a(11) =405a(12) =675a(13) =1125a(14) =1875a(15) =3125a(16) =5000a(17) =8000a(18) =12800a(19) =20480a(20) =32768a(21) =53248a(22) =86528a(23) =140608a(24) =228488a(25) =371293a(26) =599781a(27) =968877a(28) =1565109a(29) =2528253