20820969

Appears in sequences

• a(n+1) is the smallest square > a(n) such that every concatenation (n > 1) is a prime.at n=20A087352
• Numbers of the form (9^i)*(13^j), with i, j >= 0.at n=32A108748
• Numbers with 35 divisors.at n=16A175745
• Numbers with prime factorization p^4*q^6.at n=16A190464
• Integers k such that both k and k^3-1 are the sum of two positive cubes (see A003325).at n=7A271717
• Squares k such that phi(k) is a cube.at n=17A358051
• Powers k^m, m > 1, where k is an Achilles number such that A053669(k) < A006530(k).at n=22A389341
• Powers k^m, m > 1, where k is an odd Achilles number.at n=5A391375