139121

Properties

Appears in sequences

• a(n) = the smallest prime divisor of A173426(n) = concatenation of (1, 2, 3,..., n, n-1, ..., 1) for n > 1; a(1) = 1.at n=48A075023
• a(n) = Sum_{d|n} d^(phi(n/d) - 1).at n=53A345268
• Lesser of twin self primes, i.e., smaller member of the pair of self primes differing by 2.at n=13A380713
• Prime numbersat n=12933