20143

Properties

Appears in sequences

• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 74 ones.at n=25A031842
• Primes at which the difference pattern X42Y (X and Y >= 6) occurs in A001223.at n=37A052164
• Primes p such that x^27 = 2 has no solution mod p, but x^9 = 2 has a solution mod p.at n=5A059354
• Primes p such that x^54 = 2 has no solution mod p, but x^18 = 2 has a solution mod p.at n=2A059666
• Primes whose digits can be arranged in increasing cyclic order - to form a substring of 123456789012345678901234567890...at n=31A068710
• Primes p such that x^9 = 2 has a solution mod p, but x^(9^2) = 2 has no solution mod p.at n=6A070185
• Five-digit primes which use each of the decimal digits 0 through 4 exactly once.at n=2A109176
• a(n) = 7^n + 5^n + 3^n - 2^n. Constants are the prime numbers in decreasing order.at n=5A135167
• Primes p2 such that p1^3 + p2^2 is an average of twin primes and p1 < p2 are consecutive primes.at n=15A138755
• Primes congruent to 24 mod 59.at n=35A142751
• Numbers k such that (sum of base-2 digits of k) = (sum of base-10 digits of k) = 10.at n=32A152207
• Square array, read by antidiagonals, where row n+1 is generated from row n by first removing terms in row n at positions {m*(m+1)/2, m>=0} and then taking partial sums, starting with all 1's in row 0.at n=49A152405
• Primes formed by rearranging five consecutive decimal digits (avoiding leading 0).at n=2A156119
• Primes p such that p*floor(p/2) - 4 and p*floor(p/2) + 4 are prime numbers.at n=28A164622
• Primes whose digits can be arranged as consecutive digits (more precisely, to form a substring of 0123456789).at n=23A177119
• Primes whose digits are a permutation of (0, ..., m) for some m.at n=2A187796
• Smallest positive integer (or 0 if no such k) with conjecturally exactly n primitive cycles of positive integers under iteration by the Collatz-like 3x-k function.at n=17A226678
• Smallest of 4 consecutive prime numbers that when represented as a simple continued fraction, generates prime numbers in the numerator and denominator, when reduced.at n=17A270884
• Numbers k such that phi(k) > phi(k+1) > phi(k+2) > phi(k+3) where phi is the Euler totient function (A000010).at n=34A326817
• Primes p such that the sum of 2^k for k such that 2^k < p and p+2^k is prime is greater than p.at n=45A345214