Number of nonempty subsets of {1,2,...,n} with no gap of length greater than 4 (a set S has a gap of length d if a and b are in S but no x with a < x < b is in S, where b-a=d).
A119407
Number of nonempty subsets of {1,2,...,n} with no gap of length greater than 4 (a set S has a gap of length d if a and b are in S but no x with a < x < b is in S, where b-a=d).
Terms
- a(0) =1a(1) =3a(2) =7a(3) =15a(4) =31a(5) =62a(6) =122a(7) =238a(8) =462a(9) =894a(10) =1727a(11) =3333a(12) =6429a(13) =12397a(14) =23901a(15) =46076a(16) =88820a(17) =171212a(18) =330028a(19) =636156a(20) =1226237a(21) =2363655a(22) =4556099a(23) =8782171a(24) =16928187a(25) =32630138a(26) =62896622a(27) =121237146a(28) =233692122a(29) =450456058
External references
- oeis: A119407