121103

Appears in sequences

• Numbers that are the product of a pair of twin primes.at n=20A037074
• Product of twin primes of form (4*k+3,4*(k+1)+1), k>=0.at n=10A071700
• Squarefree numbers k such that A076341(k) = 0.at n=26A076352
• a(n) = prime(2*n-1)*prime(2*n).at n=34A089581
• Numbers k such that k+1 and sigma(k)+1 are both perfect squares.at n=26A089954
• Odd numbers k that divide Lucas(k) + 1.at n=32A094399
• Numbers k that divide both Fibonacci(k+1) and Lucas(k) + 1.at n=23A094402
• Odd numbers k that divide Fibonacci(k) - 1 but not Fibonacci(k-1).at n=25A094409
• Numbers k that divide Fibonacci(k+1) but do not divide Fibonacci(k) + 1.at n=33A094412
• Numbers that are one less than a square and have exactly 4 divisors.at n=21A134020
• Semiprimes k that divide Fibonacci(k+1).at n=21A177745
• Semiprimes which are sub-perfect powers.at n=30A189045
• Numbers k that form a primitive Pythagorean triple with k' and sqrt(k^2 + k'^2), where k' is the arithmetic derivative of k.at n=23A210503
• Increasing a(n)is the smallest number of the form p^a*q^b, where a,b are positive integers and p < q are odd primes such that max( p^a, q^b)/min( p^a, q^b) <= 1 + 2/prime(n).at n=36A229108
• G-Lehmer numbers: Composite numbers k such that A060968(k) divides A201629(k).at n=14A235864
• Numbers n which are neither a prime nor a square of a prime such that there is no d, 2<=d<=n/2, which divides binomial(n-d-1,d-1) and is not coprime to n.at n=29A269135
• Product of the prime numbers that are between 10*n and 10*(n+1).at n=34A356690
• Numbers k for which k^2 + (k')^2 is a square, where k' is the arithmetic derivative of k (A003415).at n=38A365850
• Numbers k such that k^2 + sopfr(k)^2 is a square, where sopfr = A001414.at n=23A386991