81540

Appears in sequences

• Number of permutations of {1,2,...,n} in which each element follows its proper divisors.at n=11A016021
• Expansion of 2/(3-sqrt(3-2*sqrt(1-4x))).at n=12A112520
• Values of n such that n^a-+a are primes, a=7.at n=23A155022