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A092446 Numbers n such that if P = 10*n^2+1, then P, P+6, P+12 and P+18 are all primes. 0

%I

%S 1,2,5,8,20,83,110,128,141,216,223,334,506,810,825,867,1086,1171,1861,

%T 2178,2295,2680,2911,3803,4884,7737,8010,8457,8520,9858,9882,10379,

%U 11871

%N Numbers n such that if P = 10*n^2+1, then P, P+6, P+12 and P+18 are all primes.

%e a(3) = 5; 10*5^2+1 = 251. 251+6 = 257; 251+12 = 263; 251+18=269. 251, 257, 263 and 269 are all primes.

%t pQ[n_]:=Module[{x=10n^2+1},And@@PrimeQ/@(x+ {0,6,12,18})]; Select[Range[12000],pQ] (* _Harvey P. Dale_, Mar 22 2011 *)

%K nonn

%O 1,2

%A _Ray G. Opao_, Mar 24 2004

%E More terms from Harvey P. Dale, Mar 22 2011.

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Last modified June 12 10:58 EDT 2021. Contains 344947 sequences. (Running on oeis4.)