Number of sequences (a_1, a_2, ..., a_n) of length n with a_1 = 1 satisfying a_i <= a_{i+1} <= 2*a_i.
A016121
Number of sequences (a_1, a_2, ..., a_n) of length n with a_1 = 1 satisfying a_i <= a_{i+1} <= 2*a_i.
Terms
- a(0) =1a(1) =2a(2) =5a(3) =17a(4) =86a(5) =698a(6) =9551a(7) =226592a(8) =9471845a(9) =705154187a(10) =94285792211
External references
- oeis: A016121