21163

Properties

Appears in sequences

• a(n)=a(n-1)+a(m), where m=2n-2-2^(p+1) and 2^p<n-1<=2^(p+1), for n >= 4.at n=31A050063
• Primes such that the sum of their digits and the sum of the reciprocals of their digits is also prime.at n=11A064779
• Primes p such that adding their adjacent digits in pairs, the digits of their index pi(p) is obtained, in some order.at n=2A115998
• Numbers k such that 15^k - 2 is a prime.at n=15A128458
• Primes congruent to 41 mod 59.at n=36A142768
• Primes congruent to 57 mod 61.at n=39A142855
• Primes obtained from other primes by pre-concatenating with 2.at n=40A165243
• Prime numbers ending in the prime number 163.at n=8A167627
• Primes of the form 10n^2 + 3.at n=15A201710
• Primes of the form 3*m^2 - 5.at n=15A201717
• G.f.: Sum_{n>=0} x^n * Product_{k=1..n} (1 + k*x) / (1 - x - k*x^2).at n=9A231291
• Primes p such that p - d and p + d are also primes, where d is the largest digit of p.at n=17A245877
• Smallest of three consecutive primes in arithmetic progression with common difference 24 and digit sum prime.at n=28A253140
• a(n) = Sum_{d|n} phi(d)*Bell(n/d) for n>0, a(0) = 0.at n=9A258171
• a(0) = 2; for n>0, a(n) = smallest prime p such that p > a(n-1) and p is congruent to n modulo prime(n).at n=41A261192
• Number of length n arrays of permutations of 0..n-1 with each element moved by -2 to 2 places and every three consecutive elements having its maximum within 5 of its minimum.at n=12A263746
• Primes whose sum of reciprocal of digits is a prime.at n=13A266815
• Primes p such that p+2^4, p+2^6 and p+2^8 are all primes.at n=27A269257
• Triangle read by rows: T(n,k) (0 <= k <= n) is the rank of the ideal I_r in the inverse semigroup D_n of all difunctional relations on an n-element set.at n=53A294432
• Positive integers m with 2*m^2 - 2^4 = x^4 + y^4 for some nonnegative integers x and y with |x-y| > 2.at n=7A343917