20981

Properties

Appears in sequences

• Primes whose digits can be arranged in increasing cyclic order - to form a substring of 123456789012345678901234567890...at n=34A068710
• a(n) = (A085249(n) - 1)/6.at n=24A088349
• Lesser of a twin-prime pair where both are expressible as the sum of two triangular numbers.at n=41A118638
• List of strictly non-palindromic twin primes {p, p+2}.at n=14A138329
• Lesser of twin primes such that both twin primes have no bases b, 1 < b < p-1, in which p is a palindrome.at n=7A138348
• Primes congruent to 36 mod 59.at n=39A142763
• Primes congruent to 58 mod 61.at n=34A142856
• Positive numbers y such that y^2 is of the form x^2+(x+191)^2 with integer x.at n=9A161487
• Least n-gap prime: a(n) = least prime p for which there is no prime between n*p and n*q, where q is the next prime after p.at n=24A195325
• Records of A195325.at n=11A195329
• Primes of the form (24*p + 1)/5, where p is a Fermat pseudoprime to base 2.at n=2A218010
• Primes p such that p+2 and q are primes, where q is concatenation of binary representations of p and p+2: q = p * 2^L + p+2, where L is the length of binary representation of p+2: L=A070939(p+2).at n=25A232238
• Primes p with p + 2 and prime(p) - 2 both prime.at n=36A236467
• Primes p such that f(f(p)) is prime, where f(x) = x^4 + x^3 + x^2 + x + 1 = A053699(x).at n=21A237445
• Initial members of prime quadruples (n, n+2, n+36, n+38).at n=19A248367
• Number of (n+2) X (5+2) 0..3 arrays with every consecutive three elements in every row and diagonal having exactly two distinct values, and in every column and antidiagonal not having exactly two distinct values, and new values 0 upwards introduced in row major order.at n=19A252716
• Primes 8k + 5 at the end of the maximal gaps in A269513.at n=13A269515
• Twin primes p such that the absolute difference of p and the reverse of its twin is a twin prime.at n=34A342216
• Lesser of twin primes p,p+2 such that the absolute difference of p and the reverse of p+2 is a twin prime and the absolute difference of p+2 and the reverse of p is a twin prime.at n=7A342299
• Primes p such that A001414(p+q) is the square of a prime, where q is the next prime after p.at n=41A342830