154770

Appears in sequences

• a(n) = smallest number k such that rk-1 is prime for all r = 1 to n.at n=5A088651
• Numbers n such that the denominator of the 2n-th Bernoulli number is divisible by n but sum_{d|n} sigma(d)/phi(d) is not an integer.at n=35A099008
• a(n) is the smallest number m such that all the n numbers 1!*m-1, 2!*m-1, ..., n!*m-1 are prime.at n=7A177013
• Least k such that x*k - 1 produces primes for x=1..n and composite for x=n+1.at n=5A202779
• Numbers k such that usigma(k) >= 3*k, where usigma(k) = sum of unitary divisors of k (A034448).at n=27A285615
• Regular triangle where T(n,k) is the number of clutters (connected antichains) on n + 1 vertices with k maximal blobs (2-connected components).at n=11A317672
• a(n) is the number of squares of side length greater than 1 having vertices at the points of an n X n grid of dots.at n=36A328152
• a(n) is the least k such that there are exactly n divisors d of k for which k/d-d is prime.at n=20A340729
• Numbers k such that A383546(k) > A383546(m) for all m < k.at n=17A383547
• Squarefree 3-abundant numbers: squarefree numbers k such that A000203(k) > 3*k.at n=27A387153