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A181542
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Numbers k such that there is at least one pair of twin primes 3^k - 3^j -+ 1 with k/2 <= j < k.
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1
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2, 3, 4, 11, 12, 18, 20, 30, 35, 47, 108, 113, 118, 127, 136, 162, 165, 212, 502, 656, 1131, 1560, 1620, 1966, 2293, 4184, 5568
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OFFSET
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1,1
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LINKS
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MAPLE
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isA181542 := proc(n) local nh, k, p; if type(n, 'even') then nh := n/2; else nh := (n+1)/2; end if; for k from n-1 to nh by -1 do p := 3^n-3^k-1 ; if isprime(p) and isprime(p+2) then return true; end if; end do ; false; end proc:
for n from 1 do if isA181542(n) then print(n); end if; end do; # R. J. Mathar, Feb 05 2011
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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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