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Search: id:A128824
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| A128824 |
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First prime which is 2k greater than the product of lesser twin primes. |
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1
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| 5, 7, 11, 13, 17, 19, 23, 37, 29, 31, 47, 37, 41, 43, 47, 61, 53, 67, 59, 61, 227, 67, 71, 73, 89, 79, 83, 97, 89, 103, 107, 97, 101, 103
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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In the example, 37 is the only number possible for 2k=22. Twinl#(1)= 3 and 3+22 = 25, not prime. Twinl#(n), n>2, is a multiple of 11 so adding 22 will always result in a multiple of 11 and not prime. If k is a multiple of a lesser twin prime, then the number of primes in twinl#(n)+2k is finite.
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FORMULA
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Define twinl#(n)as the product of the first n lesser twin primes. Then if twinl#+2k k=1,2,3... is prime, list it.
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EXAMPLE
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Twinl#(2) + 2*11 = 37, the first prime 22 greater than twinl#(2).
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PROGRAM
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(PARI) twiprimesl(n, a) = { local(pr, x, y, j); for(j=1, n, pr=1; for(x=1, j, pr*=twinl(x); ); y=pr+a; if(ispseudoprime(y), print1(y", ") ) ) } twinl(n) = \The n-th lower twin prime { local(c, x); c=0; x=1; while(c<n, if(isprime(prime(x)+2), c++); x++; ); return(prime(x-1)) }
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CROSSREFS
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Adjacent sequences: A128821 A128822 A128823 this_sequence A128825 A128826 A128827
Sequence in context: A101635 A118941 A096547 this_sequence A098420 A093495 A093496
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KEYWORD
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nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)hotmail.com), May 08 2007
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