250231

Appears in sequences

• Position of second appearance of set of first n terms in the sequence of odd primes modulo 4.at n=17A202025
• a(n) is the smallest squarefree semiprime that belongs to a sequence of length n under repeated iteration of the map (k -> concatenation of prime divisors of k in increasing order) until a number is reached that is not a squarefree semiprime.at n=9A243843