45420

Appears in sequences

• a(n) is the least k such that k*Mrs(n)*Mrs(n+1)*Mrs(n+2) + 1 is prime, where Mrs(n) is the n-th Mersenne prime.at n=20A082747
• Indices of primes in sequence defined by A(0) = 71, A(n) = 10*A(n-1) + 31 for n > 0.at n=17A101139
• Number of 4-step one space leftwards or up, two space rightwards or down asymmetric rook's tours on an n X n board summed over all starting positions.at n=29A187299
• Number of right triangles on a (n+1)X7 grid.at n=25A189811
• Smallest number k such that k*n +/- 1, k*n^2 +/- 1, and k*n^3 +/- 1 are three sets of twin primes. a(n) = 0 if no such number exists.at n=26A239021
• Numbers k such that Bernoulli number B_{k} has denominator 56786730.at n=7A295598
• T(n, k) = [x^k] M(n)*Sum_{k=0..n} E2(n, k)*binomial(-x + n - k, 2*n), where E2 are the second-order Eulerian numbers A340556 and M(n) are the Minkowski numbers A053657. Triangle read by rows, T(n, k) for n >= 0 and 0 <= k <= 2*n+1.at n=19A341111
• a(1) = 1 for the single prime 3; for n>=2, a(n) is the number of primes between 2^n and 2^(n+1) whose pairs lay symmetrically at each side of the center 3*2^(n-1) of that interval.at n=21A387095