51871

Properties

Appears in sequences

• Smallest prime factor of n!-1 (for n>2), a(2)=1.at n=21A054415
• Smaller of the two factors of the n-th semiprime number of the form m!-1.at n=6A080802
• a(n) = A000040(A096480(n)).at n=31A096481
• Noncomposite numbers in the northern ray of the Ulam spiral as oriented on the March 1964 cover of Scientific American.at n=20A168023
• Number of n X 2 arrays containing 2 copies of 0..n-1 with no equal vertical neighbors and new values introduced sequentially from 0.at n=6A265229
• T(n,k)=Number of nXk arrays containing k copies of 0..n-1 with no equal vertical neighbors and new values introduced sequentially from 0.at n=34A265232
• T(n,k)=Number of nXk arrays containing k copies of 0..n-1 with no equal diagonal or antidiagonal neighbors and new values introduced sequentially from 0.at n=34A265656
• Triangle read by rows giving the number of configurations of n indistinguishable pairs placed on the vertices of the ladder graph P_2 X P_n such that exactly k such pairs are joined by a horizontal edge.at n=28A325754
• Prime numbersat n=5308