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A241488
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Primes p such that p+8, p+888 and p+8888 are also prime.
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1
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53, 263, 389, 431, 983, 1013, 1061, 1223, 1571, 1823, 2789, 3323, 3533, 3911, 4211, 5849, 6563, 6653, 7019, 7481, 8369, 8963, 9041, 9173, 9413, 9539, 9803, 10091, 10559, 10979, 12611, 12689, 12911, 13163, 13751, 13781, 14243, 14879, 15083, 16691, 17231, 17483
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OFFSET
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1,1
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COMMENTS
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All the terms in the sequence are congruent to 2 mod 3.
The constants in the definition (8, 888 and 8888) are the concatenation of digit 8.
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LINKS
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EXAMPLE
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a(1) = 53 is a prime: 53+8 = 61, 53+888 = 941 and 53+8888 = 8941 are also prime.
a(2) = 263 is a prime: 263+8 = 271, 263+888 = 1151 and 263+8888 = 9151 are also prime.
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MAPLE
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KD:= proc() local a, b, d, e; a:= ithprime(n); b:=a+8; d:=a+888; e:=a+8888; if isprime(b)and isprime(d)and isprime(e) then return (a) :fi; end: seq(KD(), n=1..5000);
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MATHEMATICA
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KD = {}; Do[p = Prime[n]; If[PrimeQ[p + 8] && PrimeQ[p + 888] && PrimeQ[p + 8888], AppendTo[KD, p]], {n, 5000}]; KD
(*For the b-file*) c = 0; p = Prime[n]; Do[If[PrimeQ[p + 8] && PrimeQ[p + 888] && PrimeQ[p + 8888], c = c + 1; Print[c, " ", p]], {n, 1, 5*10^6}];
Select[Prime[Range[2500]], AllTrue[#+{8, 888, 8888}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jul 31 2017 *)
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PROG
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(PARI) s=[]; forprime(p=2, 18000, if(isprime(p+8) && isprime(p+888) && isprime(p+8888), s=concat(s, p))); s \\ Colin Barker, Apr 25 2014
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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