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Search: id:A080699
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| A080699 |
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Product of twin-prime-index-primes and their upper bound twin prime. |
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+0
1
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| 25, 77, 403, 1121, 3379, 7697, 16897, 25769, 56341, 63983, 107447, 129709, 192403, 222529, 238999, 328157, 361259, 466933, 515909, 645719, 817009, 1219637, 1299433, 1508917, 1952359, 2359943, 2642597, 2815831, 3060037, 3260713
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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Let p(i) =i-th prime, let twin(n) = (P, Q) be n-th pair of twin primes; sequence gives p(P)*Q.
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EXAMPLE
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The 3rd pair of twin primes is twin(3) = (11,13), p(11) = 31 Seq(3) = 31*13 = 403
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PROGRAM
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(PARI) twipxpindex2(n) = {sr=0; pr=1; for(x=1, n, p1=prime(x); p2=prime(x+1); if((p2-p1)==2, pr=p2*prime(prime(x)); sr+=1.0/pr; print1(pr" ")); ); print(); print(sr) }
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CROSSREFS
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Cf. A057470.
Sequence in context: A042228 A042230 A033658 this_sequence A134153 A016814 A100487
Adjacent sequences: A080696 A080697 A080698 this_sequence A080700 A080701 A080702
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KEYWORD
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easy,nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)gmail.com), Mar 04 2003
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