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A265629
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Numbers k > 0 such that 10^(k+4) - 23 is prime.
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2
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OFFSET
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1,1
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COMMENTS
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Numbers k such that '9977' appended to k times the digit 9 is prime.
Up to a(8) the terms themselves are primes.
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LINKS
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FORMULA
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EXAMPLE
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7 appears because 99999999977 ('9' concatenated 7 times and prepended to '9977') is prime.
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MAPLE
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A265629:=n->`if`(isprime((10^(n+4) - 23), n, NULL): seq(A265629(n), n=1..1000)
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MATHEMATICA
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Select[ Range[10^3], PrimeQ[10^(# + 4) - 23] &]
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PROG
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(Magma) [n: n in [1..200] | IsPrime((10^(n+4) - 23)];
(PARI) is(n)=isprime(10^(n+4) - 23)
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CROSSREFS
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KEYWORD
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nonn,base,more
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AUTHOR
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STATUS
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approved
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