20693

Properties

Appears in sequences

• Incorrect duplicate of A297408.at n=21A007355
• a(0) = 1, a(n) = 19*n^2 + 2 for n>0.at n=33A010009
• 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 12.at n=15A031600
• Primes such that the sum of the factorials of the digits is a perfect square.at n=34A052279
• Primes of the form k^2 + prime(k) + 1.at n=12A063461
• Primes p such that q = 4p^2 + 1 and r = 4q^2 + 1 are also prime.at n=30A122424
• Primes of the form a^2 + b^2 + c^2 such that a^4 + b^4 + c^4 is prime as well and larger than the first one.at n=36A126118
• Primes congruent to 14 mod 61.at n=37A142812
• Primes p of the form 4*k+1 for which s=26 is the least positive integer such that s*p-(floor(sqrt(s*p)))^2 is a square.at n=25A145050
• Primes p such that continued fraction of (1 + sqrt(p))/2 has period 11: primes in A146335.at n=31A146356
• The number of patterns of non-papaya words.at n=8A165610
• Primes whose reversal - 1 is a square.at n=33A167218
• Triangle T(n,k) = binomial(n,k) + A176490(n,k) - 1 read along rows 0<=k<=n.at n=46A176491
• Primes of form a^2+b^2 such that a^4+b^4 and a^8+b^8 are primes.at n=16A182313
• Number of inequivalent (mod D_4) ways to place 2 nonattacking knights on an n X n board.at n=22A243717
• Fundamental discriminants d uniquely characterizing all complex biquadratic fields Q(sqrt(-3),sqrt(d)) which have 3-class group of type (3,3) and second 3-class group isomorphic to SmallGroup(729,34).at n=7A250241
• Primes 8k + 5 at the end of the maximal gaps in A269513.at n=12A269515
• Primes p such that 2*p+1 and 4*p^2+1 are also prime.at n=28A333803
• Primes p such that p+1 is a triprime and 2*p+1 is prime.at n=37A386295
• Prime numbersat n=2330