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A357280
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Smallest m such that m^k-2 and m^k+2 are prime for k=1..n.
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0
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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) = 102795 because:
for k = 1; 102795^1-2 = 102793 and 102795^1+2 = 102797, both of which are prime, and
for k = 2; 102795^2-2 = 10566812023 and 102795^2+2 = 10566812027, both of which are prime, and
for k = 3; 102795^3-2 = 1086215442109873 and 102795^3+2 = 1086215442109877, both of which are prime, and
102795 is the smallest number with this property.
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PROG
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(PARI) isok(m, n) = for (k=1, n, if(!isprime(m^k-2) || !isprime(m^k+2), return(0)); ); return(1);
a(n) = my(m=1); while(!isok(m, n), m++); m; \\ Michel Marcus, Nov 14 2022
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CROSSREFS
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KEYWORD
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nonn,more,hard
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AUTHOR
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STATUS
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approved
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