20431

Properties

Appears in sequences

• Positive numbers k such that k and 2*k are anagrams in base 6 (written in base 6).at n=21A023064
• Primes that are palindromic in base 5.at n=28A029973
• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 94 ones.at n=21A031862
• Smallest prime factor of n!-1 (for n>2), a(2)=1.at n=24A054415
• Primes whose digits can be arranged in increasing cyclic order - to form a substring of 123456789012345678901234567890...at n=33A068710
• a(n) = A075443(A075451(n)).at n=30A075452
• Smaller of the two factors of the n-th semiprime number of the form m!-1.at n=8A080802
• Numerator of n*sum(k=1,(-1)^(k+1)/(n+k)).at n=7A082689
• Five-digit primes which use each of the decimal digits 0 through 4 exactly once.at n=4A109176
• Primes p such that 42*p-1, 42*p+1 and 48*p-1, 48*p+1 are twin primes.at n=7A138697
• Primes congruent to 17 mod 59.at n=38A142744
• Primes congruent to 57 mod 61.at n=38A142855
• Primes formed by rearranging five consecutive decimal digits (avoiding leading 0).at n=4A156119
• Primes whose digits can be arranged as consecutive digits (more precisely, to form a substring of 0123456789).at n=25A177119
• Primes which are the fourth element of a generalized Wieferich sequence.at n=10A179400
• Primes which are the fifth element of a generalized Wieferich sequence.at n=4A179678
• Primes whose digits are a permutation of (0, ..., m) for some m.at n=4A187796
• Primes whose digits add to 10 and which have a 3 in the tens place.at n=11A227825
• Numerators of the Nielsen-Jacobsthal series leading to Euler's constant.at n=2A262856
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 805", based on the 5-celled von Neumann neighborhood.at n=25A273604