30593

Properties

Appears in sequences

• a(0)=2; for n>=1, a(n) = smallest prime p such that there is a gap of exactly 2n between p and next prime, or -1 if no such prime exists.at n=19A000230
• Numbers k such that 6!*(2*k-7)!/(k!*(k-1)!) is an integer.at n=32A004786
• Numbers k such that 7!*(2k-8)!/(k!*(k-1)!) is an integer.at n=36A004787
• Number of binary rooted trees with n nodes and height at most 6.at n=24A036589
• Numbers k such that k^3 is a cube whose digits occur with an equal minimum frequency of 2.at n=23A052051
• First n-digit prime to begin a gap.at n=4A053299
• n satisfying sigma(n+1) = sigma(n-1).at n=33A055574
• a(n) = Min{ q prime | nextprime(q) - q - 1 = prime(n)}, or 0 if none exist.at n=10A063793
• Numbers n such that sigma (phi ( n ) ) = sigma (sigma (n ) ) where phi is Euler's totient and sigma is the multiplicative sum-of-divisors function.at n=17A065556
• Numbers k such that sigma(k-1) divides sigma(k+1).at n=39A067130
• Primes p such that sigma(p+1) = sigma(p-1).at n=2A067891
• Duplicate of A067891.at n=2A068357
• Smallest prime p such that there is a gap of exactly 2*prime(n) between p and the next prime.at n=7A080082
• a(n) is the smallest prime p such that the largest prime divisor of the difference nextprime(p) - p equals the n-th prime, prime(n).at n=7A081413
• Increasing peaks in the prime gap sequence A000230.at n=3A086977
• a(n) = prevprime(A090117(n)), the largest prime previous to squares given in A090117, being such that distance of a(n) to the following prime equals 2*n.at n=18A090118
• Primes of the form 256n+129.at n=27A105130
• prime(k) for those k where floor((2*(prime(k+1)-prime(k))*PrimePi(k) mod (8*k))/k) = m with m = 10.at n=32A109564
• Numbers appearing in A122072 at least four times.at n=17A122390
• Records in A000230.at n=13A133429