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A065317
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Largest prime divisor of the sum of the n-th primorial and the (n+1)-st prime.
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4
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5, 11, 37, 17, 101, 30047, 510529, 9699713, 1427, 76829, 789077, 659863, 810104837, 13082761331670077, 652833094897, 32589158477190044789, 1922760350154212639131, 28406001782370300553, 770555057, 94904036422299534098897, 40729680599249024150621323549
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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For n = 4, 4th primorial = 210, prime(5) = 11, sum = 210 + 11 = 13 * 17, a(4) = 17.
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MATHEMATICA
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With[{nn=20}, FactorInteger[#][[-1, 1]]&/@(Total/@Thread[{FoldList[ Times, Prime[Range[nn]]], Prime[Range[nn]+1]}])] (* Harvey P. Dale, Jul 26 2020 *)
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PROG
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(PARI) a(n) = vecmax(factor(vecprod(primes(n)) + prime(n+1))[, 1]); \\ Daniel Suteu, May 26 2022
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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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