70321

Properties

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 21.at n=25A031609
• a(n) = a(n-2) + a(n-4) + a(n-5) + a(n-7) + a(n-8) + a(n-10) for n >= 10, with a(0) = ... = a(9) = 1.at n=36A122762
• Number of 0..n arrays x(0..3) of 4 elements with nondecreasing average value and 0..n occur with instance counts within one of each other.at n=27A200943
• Primes p such that 2p^2-1, 3p^2-2 and 4p^2-3 are also prime.at n=24A213079
• Primes p such that 2p^2-1, 3p^2-2, 4p^2-3, and 5p^2-4 are also prime.at n=2A213107
• Strong (2,3,5)-primes (see comments).at n=34A262727
• Prime numbersat n=6970