223439

Properties

Appears in sequences

• Lesser of twin primes (p,q=p+2) such that p*q-p-q and p*q+p+q are primes.at n=19A126334
• Numbers k such that prime(k) * 2^k - 1 is prime.at n=26A239741
• Triangle read by rows: T(n,k) (0 <= k <= n) is the rank of the ideal I_r in the inverse semigroup D_n of all difunctional relations on an n-element set.at n=60A294432
• a(n) is the least prime p such that (p^2-2*n)/(2*n-1) and (p^2+2*n)/(2*n+1) are both prime, or 0 if such p does not exist.at n=23A344463
• Primes p such that if q is the next prime, the sum (with multiplicity) of prime factors of p^2 + q^2 is a square.at n=40A359443
• Primes whose second, third and fourth digits are 234.at n=25A371833
• Prime numbersat n=19898