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A253682
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Prime sums of three distinct Mersenne primes (A000668).
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0
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OFFSET
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1,1
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COMMENTS
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a(1) has the exponents of the three distinct Mersenne primes of 1, 2 and 3; a(2) the exponents are 1, 2 and 4, a(3) the exponents are 1, 4 and 8 and a(4) the exponents are 1, 10 and 11. - Robert G. Wilson v, Jan 08 2015
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LINKS
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EXAMPLE
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a(3) = 2147483777 because 2147483777 = (2^2-1) + (2^7-1) + (2^31-1).
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MATHEMATICA
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exp={* the first 34 terms in A000043 *}; Do[ s = 2^exp[[p]] + 2^exp[[q]] + 2^exp[[r]] - 3; If[ PrimeQ@ s, Print[{p, q, r, s}]], {r, 3, 34}, {q, 2, r - 1}, {p, q - 1}] (* Robert G. Wilson v, Jan 08 2015 *)
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CROSSREFS
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KEYWORD
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nonn,hard
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AUTHOR
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STATUS
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approved
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