27644436
domain: N
Appears in sequences
- a(n) = B(n) - 1, where B(n) = Bell numbers, A000110.at n=11A058692
- Number of primitive (aperiodic) word structures of length n using an infinite alphabet.at n=13A082951
- a(n) = Phi(Bell(n)).at n=13A131637
- Number of set partitions of {1, ..., n} that avoid enhanced 7-crossings (or enhanced 7-nestings).at n=13A192867
- Number of arrays of n 0..11 integers with new values introduced in order 0..11 but otherwise unconstrained.at n=12A203642
- Number of set partitions of [n] such that j is member of block b only if b = 1 or at least one of j-1, ..., j-10 is member of a block >= b-1.at n=13A287673
- a(n) = Sum_{k=1..n, gcd(n,k) = 1} Stirling2(n,k).at n=12A308463
- Number of set partitions of {1,...,n} with relatively prime block sizes.at n=13A318120
- a(n) = n! * [x^n] exp(Sum_{k=1..n, gcd(n,k) = 1} x^k / k!).at n=13A335797