Number of subsets of {1..n} where some element is a difference of two consecutive elements.

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =6a(5) =14a(6) =34a(7) =74a(8) =164a(9) =345a(10) =734a(11) =1523a(12) =3161a(13) =6488a(14) =13302a(15) =27104a(16) =55150a(17) =111823a(18) =226443a(19) =457586a(20) =923721a(21) =1862183a(22) =3751130a(23) =7549354a(24) =15184291a(25) =30521675a(26) =61322711a(27) =123151315a(28) =247230601a(29) =496158486