92372
domain: N
Appears in sequences
- Least k such that k*Mersenne-prime(n)-1 is prime.at n=27A098555
- Nearest k to j such that k*(2^j-1)-1 is prime where j=A000043(n) and 2^j-1 = Mersenne-prime(n) = A000668(n). If there are two k values equidistant from j, each of which produces a prime, the larger of the two gets added to the sequence.at n=27A101416
- Number T(n,k) of Dyck paths of semilength n having exactly k (possibly overlapping) occurrences of the consecutive steps UUDDUDUUUUDUDDDDUUDD (with U=(1,1), D=(1,-1)); triangle T(n,k), n>=0, 0<=k<=max(0,floor((n-2)/8)), read by rows.at n=30A242450
- Let P(n) = primorial(n) = A002110(n); a(n) is the number of primes q < P(n) such that P(n) - q is also prime and q^2==1 (mod P(n)).at n=23A336093