A245048 Primes p such that p^2 + 28 is prime.
3, 5, 11, 13, 17, 19, 23, 41, 43, 47, 53, 67, 79, 83, 89, 97, 109, 131, 137, 149, 157, 163, 167, 179, 181, 193, 211, 223, 239, 241, 251, 263, 277, 281, 311, 317, 331, 379, 397, 401, 409, 421, 431, 439, 443, 449, 457, 467, 479, 541, 569, 599, 643, 647, 673
Offset: 1
Keywords
Examples
3 is in the sequence because 3^2 + 28 = 37, which is also prime. 5 is in the sequence because 5^2 + 28 = 53, which is also prime. 7 is not in the sequence because 7^2 + 28 = 77 = 7 * 11.
Links
- Chai Wah Wu, Table of n, a(n) for n = 1..2000
Programs
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Maple
A245048:=n->`if`(isprime(n) and isprime(n^2+28), n, NULL): seq(A245048(n), n=1..10^3); # Wesley Ivan Hurt, Jul 24 2014
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Mathematica
Select[Prime[Range[200]], PrimeQ[#^2 + 28] &] (* Alonso del Arte, Jul 12 2014 *)
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Python
import sympy [sympy.prime(n) for n in range(1,10**6) if sympy.ntheory.isprime(sympy.prime(n)**2+28)]
Comments