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A336773
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a(n) is the least prime of the form 2^j*3^k + 1, j > 0, k > 0, j + k = n. a(n) = 0 if no such prime exists.
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5
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7, 13, 37, 73, 97, 193, 577, 769, 3457, 10369, 0, 12289, 629857, 839809, 147457, 995329, 1990657, 786433, 5308417, 120932353, 14155777, 28311553, 0, 113246209, 29386561537, 3439853569, 6879707137, 1811939329, 18345885697, 3221225473, 1253826625537, 0, 85691213438977
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OFFSET
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2,1
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LINKS
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MAPLE
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f:= proc(n) local k, p;
for k from 1 to n-1 do
p:= 2^(n-k)*3^k+1;
if isprime(p) then return p fi
od;
0
end proc:
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PROG
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(PARI) for(n=2, 34, my(pm=oo); for(j=1, n-1, my(k=n-j, p=2^j*3^k+1); if(isprime(p), pm=min(p, pm))); print1(if(pm==oo, 0, pm), ", "))
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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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