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A227890
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Primes of the form prime(k)^2 - k.
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1
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3, 7, 163, 353, 5021, 12739, 32719, 49681, 52391, 78901, 113501, 252913, 361091, 452807, 551917, 993841, 1559797, 1956979, 2193127, 3463037, 4067983, 5003837, 5138953, 6115363, 6723271, 7251857, 7447043, 7578607, 8426989, 9479801, 11295847, 12186593, 12439237
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OFFSET
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1,1
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LINKS
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EXAMPLE
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a(3)= 163: prime(6)^2 - 6= 13^2 - 6= 169 - 6= 163 which is prime.
a(4)= 353: prime(8)^2 - 8= 19^2 - 8= 361 - 8= 353 which is prime.
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MAPLE
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with(numtheory):KD := proc() local a; a:= (ithprime(k)^2-k); if isprime(a) then RETURN (a); fi; end: seq(KD(), k=1..1000);
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MATHEMATICA
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Select[Table[Prime[k]^2-k, {k, 1000}], PrimeQ]
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PROG
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(PARI) for(k=1, 10^5, if(ispseudoprime(KD=((prime(k)^2-k))), print1(KD", ")));
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CROSSREFS
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Cf. A184935 (primes: k^2 + prime(k)).
Cf. A188831 (primes: k^2 - prime(k)).
Cf. A229203 (primes: k^3 - prime(k)).
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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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