OFFSET
1,1
COMMENTS
Consider 4 distinct numbers a, b, c, d such that all 5 numbers a+b+c+d, -a+b+c+d, a-b+c+d, a+b-c+d and a+b+c-d are positive/negative primes. The sequence give values of d for fixed values a=3, b=4, c=6.
Apparently a=3, b=4, c=6 is the least possible set.
LINKS
Zak Seidov, Table of n, a(n) for n = 1..1000
MATHEMATICA
Reap[Do[If[PrimeQ[a + b - c + d] && PrimeQ[a - b + c + d] && PrimeQ[-a + b + c + d] && PrimeQ[a + b + c - d] && PrimeQ[a + b + c + d], Sow[d]], {a, 3, 3}, {b, 4, 4}, {c, 6, 6}, {d, 1 + c, 100000}]][[2, 1]]
fQ[n_] := Times @@ Boole@ PrimeQ[{n +13, n +7, n +5, n +1, n -13}] == 1; Select[6 + 30*Range[2, 13100], fQ] (* Robert G. Wilson v, Feb 03 2017 *)
PROG
(PARI) is(n)=isprime(n-13) && isprime(n+1) && isprime(n+5) && isprime(n+7) && isprime(n+13) \\ Charles R Greathouse IV, Feb 06 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Feb 02 2017
EXTENSIONS
New NAME from Charles R Greathouse IV, Feb 06 2017
STATUS
approved