665279

Properties

Appears in sequences

• Primes p such that p+1 is a highly composite number.at n=18A072828
• Chen primes p such that p + 2 is triangular.at n=27A109504
• Chen primes p such that their p + 2 counterpart is a Sarrus number (pseudoprime to base 2).at n=19A109994
• Primes of the form (2*n)!/n!-1.at n=1A112854
• a(n)= numerator of ((n + 3)! - (n - 3)!)/(n!).at n=6A127227
• Primes which produce records in A157188, at index i=pi(a(n)) (pi=A000720).at n=13A157190
• a(n) is the smallest prime such that exactly n prime pairs (p,q) exist with a(n) = p * q + p + q.at n=19A198277
• Primes p such that 2*p + 1 is also prime and p + 1 is a highly composite number (definition 1).at n=10A214873
• The least number having n representations as p*q - p - q for primes p <= q.at n=19A218862
• Numbers k where records occur for d(k+1)/d(k), where d(k) is A000005(k).at n=28A282531
• Primes p for which sigma(p+1)/sigma(p) reaches a record value, where sigma(k) is the divisor sum function (A000203).at n=22A326393
• Numbers k where records occur for sigma(k+1)/sigma(k), where sigma(k) is the sum of divisors of k (A000203).at n=17A335067
• a(n) is the least prime p such that there are exactly n pairs of primes (q,r) with p > q > r such that q | r + p and r | q + p.at n=21A344776
• Numbers k such that, via a residue based measure M(k) (see Comments), k is deficient, k+1 is abundant, and abs(M(k)) + abs(M(k+1)) reaches a new maximum.at n=23A362083
• a(n) is the least number that occurs exactly n times in A075255.at n=20A385964
• Prime numbersat n=53972