Number of subsets S of {1,2,3,...,n} with the property that if x is a member of S then at least one of x/2 and 2x is also a member of S.
A172148
Number of subsets S of {1,2,3,...,n} with the property that if x is a member of S then at least one of x/2 and 2x is also a member of S.
Terms
- a(0) =1a(1) =2a(2) =2a(3) =4a(4) =4a(5) =8a(6) =8a(7) =14a(8) =14a(9) =28a(10) =28a(11) =56a(12) =56a(13) =112a(14) =112a(15) =192a(16) =192a(17) =384a(18) =384a(19) =768a(20) =768a(21) =1536a(22) =1536a(23) =2688a(24) =2688a(25) =5376a(26) =5376a(27) =10752a(28) =10752a(29) =21504
External references
- oeis: A172148