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A277312
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Smallest k such that k - lambda(k) = prime(n), where lambda(k) = A002322(k).
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1
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4, 9, 25, 49, 15, 169, 289, 361, 33, 841, 961, 1369, 1681, 1849, 69, 65, 87, 3721, 4489, 115, 5329, 91, 123, 7921, 9409, 10201, 10609, 159, 11881, 12769, 16129, 215, 18769, 19321, 185, 22801, 24649, 26569, 249, 221, 267, 32761, 329, 37249, 38809, 39601, 247, 259, 339, 52441
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OFFSET
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1,1
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COMMENTS
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a(n) <= prime(n)^2, because p^2 - lambda(p^2) = p prime.
Conjecture: a(n) = prime(n)^2 for infinitely many n.
For n > 1, a(n) is an odd composite. - Robert Israel, Oct 14 2016
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LINKS
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MAPLE
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N:= 100: # to get a(1)..a(N)
A:= Vector(N):
A[1]:= 4:
count:= 1:
for k from 9 by 2 while count < N do
r:= k - numtheory:-lambda(k);
if isprime(r) then
n:= numtheory:-pi(r);
if n <= N and A[n] = 0 then
count:= count+1;
A[n]:= k;
fi
fi
od:
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MATHEMATICA
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Table[k = 1; While[k - CarmichaelLambda@ k != Prime@ n, k++]; k, {n, 50}] (* Michael De Vlieger, Oct 14 2016 *)
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PROG
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(PARI) a(n) = {my(k = 1); while (k - lcm(znstar(k)[2]) != prime(n), k++); k; } \\ Michel Marcus, Oct 09 2016
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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