22721

Properties

Appears in sequences

• Primes p such that p+1 is palindromic.at n=34A028981
• Primes p from A031924 such that A052180(primepi(p)) = 31.at n=6A052237
• Primes of the form a^2 + b^2 + c^2 such that a^4 + b^4 + c^4 is prime as well and larger than the first one.at n=38A126118
• Primes of form a^2+b^2 such that a^4+b^4 and a^8+b^8 are primes.at n=18A182313
• Number of strings of numbers x(i=1..8) in 0..n with sum i^2*x(i)^2 equal to n^2*64.at n=10A184246
• Prime numbers whose central digit equals the sum of the other digits.at n=21A235119
• Prime-Indexed Primes (PIPs) k such that the sum of all PIPs <= k is a prime.at n=38A261148
• a(n) = Sum_{k=1..n} C(n, floor((n-k)/k)).at n=17A273160
• Total number of divisors d of m (counted with multiplicity), such that the prime signature of d is a partition of three and m runs through the set of least numbers whose prime signature is a partition of n.at n=14A309693
• Primes p such that if q is the next prime, p+A004086(q) and q+A004086(p) are prime.at n=20A351728
• a(n) = Sum_{k=0..n} (-1)^k*A001595(k)^2.at n=10A375501
• Prime numbersat n=2539