2695680

Appears in sequences

• Number of double-free subsets of {1, 2, ..., n}.at n=26A050291
• Modified linear phone booth sequence: number of ways to occupy n phone booths in a row, one by one, each time picking a phone booth adjacent to the smallest number of previously occupied phone booths.at n=11A192008
• a(n) = n! / Product_{p prime < n}.at n=13A300902