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 A281937 Numbers k such that k - 13, k + 1, k + 5, k + 7, and k + 13 are all prime. 1
 66, 96, 1446, 2706, 7206, 9336, 11826, 19416, 21516, 28656, 42696, 52176, 71706, 79146, 81546, 88806, 126486, 136986, 140676, 151896, 159786, 167436, 188856, 222786, 223836, 245976, 266676, 272346, 284736, 330426, 340926, 349926, 375246, 375996, 389526, 395106 (list; graph; refs; listen; history; text; internal format)
 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 Sequence in context: A098775 A109759 A194196 * A109141 A350197 A350204 Adjacent sequences: A281934 A281935 A281936 * A281938 A281939 A281940 KEYWORD nonn AUTHOR Zak Seidov, Feb 02 2017 EXTENSIONS New NAME from Charles R Greathouse IV, Feb 06 2017 STATUS approved

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Last modified April 22 09:38 EDT 2024. Contains 371894 sequences. (Running on oeis4.)