81199

Properties

Appears in sequences

• Let f(n) = number of ways to factor n = A001055(n); a(n) = sum of f(k) over all terms k in A025487 that have n factors.at n=8A035310
• a(n) = a(1) + a(2) + ... + a(n-1) + a(m) for n >= 4, where m = n - 1 - 2^p and p is the unique integer such that 2^p < n-1 <= 2^(p+1), with a(1) = 1, a(2) = 3, and a(3) = 4.at n=16A049978
• a(1) = 2; a(n) = smallest prime > a(n-1) such that the sum of any three nondecreasing terms, chosen from a(1), ..., a(n-1) and a(n), is unique.at n=26A060276
• Primes which yield a prime whenever a 1 is inserted anywhere in them (including at the beginning or end).at n=30A069246
• a(2*n+1) = 9*a(n), a(2*n+2) = 10*a(n) + a(n-1).at n=36A116555
• Primes having only {1, 8, 9} as digits.at n=39A385783
• Prime numbersat n=7948