20087

Appears in sequences

• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 21 ones.at n=12A031789
• Numbers k such that 2^k + k^3 is prime.at n=8A058015
• Numerators of the convergents to log_2(5).at n=7A116985
• a(n) = 62*n^2 - 1.at n=17A158680
• Numbers k such that 210*k+{11, 13, 17, 19, 23, 29} are 6 consecutive primes.at n=12A182282
• Numbers k such that 10^k + 109 is prime.at n=10A258933
• Numbers which are palindromic in their Elias delta code representation.at n=40A281380
• Odd composite integers m such that U(m)^2 == 1 (mod m) and V(m) == 5 (mod m), where U(m)=A004254(m) and V(m)=A003501(m) are the m-th generalized Lucas and Pell-Lucas numbers of parameters a=5 and b=1, respectively.at n=36A337779
• Odd composite integers m such that A004254(m-J(m,21)) == 0 (mod m) and gcd(m,21)=1, where J(m,21) is the Jacobi symbol.at n=38A340098