20011

Properties

Appears in sequences

• a(n) = 1 + a(floor(n/2))*a(ceiling(n/2)) for n > 1, a(1) = 4.at n=6A005511
• Primes that remain prime through 3 iterations of function f(x) = 6x + 1.at n=17A023287
• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 76 ones.at n=34A031844
• Primes having only {0, 1, 2} as digits.at n=14A036953
• Lexicographically earliest strictly increasing base 3 autovarious sequence: a(n) = number of distinct a(k) mod 3^n (written in base 3).at n=22A037091
• Primes with 12 as smallest positive primitive root.at n=6A061325
• Luhn primes: primes p such that p + (p reversed) is also a prime.at n=27A061783
• Primes whose sum of digits is 4.at n=9A062339
• Smallest n-digit prime starting with a 2.at n=4A069590
• Numbers k such that k, sigma(k) and phi(k) have the same decimal digits (ignoring multiplicity).at n=22A082059
• Prime numbers such that first reversing digits and after squaring equals the result of first-squaring and after-reversing. Primes in A085305.at n=28A085306
• Primes with maximal digit = 2.at n=11A106100
• Primes in increasing order with most significant digit following the cyclic pattern 2,3,5,7,2,3,5,7,2,3,5,7,...at n=16A113611
• a(n) = smallest n-digit prime which differs from the previous n-digit prime at every corresponding digit (or 0 if no such prime exists).at n=4A114017
• Prime values of integers written in factorial base, interpreted as in base 10.at n=37A121402
• Centered triangular numbers that are prime.at n=26A125602
• Numbers k such that 3 and 5 do not divide binomial(2*k, k).at n=46A129508
• Primes congruent to 10 mod 59.at n=37A142737
• Primes where the first digit equals the sum of all the other digits.at n=23A156307
• Primes sorted on digit sums, then on the primes.at n=13A157715