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A080700
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Product of upper bound twin-prime-indexed primes and their lower bound twin prime.
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0
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33, 85, 451, 1139, 3683, 7831, 16697, 26057, 56863, 64093, 109189, 130673, 194573, 223661, 239749, 328469, 363997, 468329, 519007, 647191, 815797, 1218871, 1301189, 1520839, 1959481, 2363057, 2648179, 2817839, 3068467, 3257437
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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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Let prime(i) = i-th prime, let twin(n) = (P, Q) be n-th pair of twin primes; sequence gives prime(Q)*P.
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EXAMPLE
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The 3rd pair of twin primes is twin(3) = (11,13), prime(13) = 41, a(3) = 41*11 = 451.
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MATHEMATICA
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Prime[Last[#]]First[#]&/@Select[Partition[Prime[Range[200]], 2, 1], Last[#]- First[#] ==2&] (* Harvey P. Dale, Apr 23 2011 *)
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PROG
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(PARI) twipxpindex3(n) = {sr=0; pr=1; for(x=1, n, p1=prime(x); p2=prime(x+1); if((p2-p1)==2, pr=p1*prime(prime(x+1)); sr+=1.0/pr; print1(pr" ")); ); print(); print(sr) }
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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