21391

Properties

Appears in sequences

• Primes that remain prime through 4 iterations of function f(x) = 10x + 9.at n=10A023329
• Prime number spiral (clockwise, Northwest spoke).at n=24A053999
• (7^n)-th prime.at n=4A058239
• Initial term in sequence of four consecutive primes whose consecutive differences have d-pattern = [6, 4, 6]; short d-string notation for pattern = [646].at n=27A078856
• Balanced primes of order seven.at n=20A096699
• a(n) = prime(n^4).at n=6A109791
• a(n) = (n^3 + 18*n^2 + 17*n + 6)/6.at n=45A143058
• Primes in A005891 = Centered pentagonal numbers: (5n^2 + 5n + 2)/2.at n=17A145838
• Primes p such that p^3 - 12 and p^3 + 12 are also primes.at n=27A153322
• Primes of the form 2n^2+18n+7, n>=0.at n=12A154592
• Primes p such that p^3-p^2-1 and p^3-p^2+1 are prime.at n=34A160858
• Primes p such that p plus or minus the sum of the fourth powers of its digits is a prime in both cases.at n=34A179595
• Total sum of Fibonacci parts in all partitions of n.at n=24A199936
• Primes p such that q = 2*p^2 - 1 and 2*p*q - 1 are also prime.at n=38A224990
• Expansion of Product_{k>=1} (1 + x^(3*k))^(3*k) / (1 + x^k)^k.at n=36A285294
• Number of compositions of n whose run-lengths cover an initial interval of positive integers.at n=16A329766
• Expansion of e.g.f. Product_{k>0} 1/(1 - sin(x)^k / k!).at n=8A335642
• The (m^n)-th prime, written as square array T(n,m) read by falling antidiagonals.at n=48A347000
• Primes p such that if q is the next prime, p+A004086(q) and q+A004086(p) are prime.at n=18A351728
• Consecutive states of the linear congruential pseudo-random number generator (1021*s + 25673) mod 121500 when started at s=1.at n=30A385341