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A353302
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Numbers k such that A004394(k)-1 and A004394(k)+1 are twin primes.
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3
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3, 4, 5, 9, 11, 12, 24, 25, 76, 82, 105, 139, 217, 1370
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OFFSET
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1,1
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COMMENTS
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a(15) > 10^5, if it exists.
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LINKS
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EXAMPLE
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3 is a term since the third superabundant number is A004394(3) = 4 and {4-1, 4+1} = {3, 5} is a twin primes pair.
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MATHEMATICA
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s = {}; abm = 0; k = 0; Do[ab = DivisorSigma[-1, n]; If[ab > abm, abm = ab; k++; If[PrimeQ[n - 1] && PrimeQ[n + 1], AppendTo[s, k]]], {n, 1, 10^6}]; s
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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