213443

Appears in sequences

• Numbers that are the product of a pair of twin primes.at n=23A037074
• Product of twin primes of form (4*k+1,4*k+3), k>0.at n=10A071697
• Numbers k that have no zero digits and such that both k+1 and (product of digits of k) + 1 are squares.at n=29A081990
• Numbers k such that k+1 and sigma(k)+1 are both perfect squares.at n=31A089954
• Numbers k equal prime(n)*prime(n+1) such that k+1 is a square and k-1 is even semiprime.at n=8A107423
• Semiprimes which are equal to product of two successive primes and also to sum of three successive primes.at n=6A133126
• Numbers that are one less than a square and have exactly 4 divisors.at n=24A134020
• Members of A159053 which are not multiples of 3.at n=13A159054
• Semiprimes which are sub-perfect powers.at n=34A189045
• 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=26A210503
• Semiprimes p*q for which p and q are successive primes and their binary representations differ from each other in one bit position only.at n=25A261080
• 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=32A269135
• Euler elliptic Carmichael numbers for the elliptic curve y^2 = x^3 + 80.at n=35A290338
• Numbers k such that k^2 + sopfr(k)^2 is a square, where sopfr = A001414.at n=26A386991