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Search: id:A120640
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| A120640 |
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Primes such that their quadruple is not 1 away from a prime number. |
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+0
1
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| 19, 23, 29, 31, 47, 59, 61, 89, 101, 103, 107, 109, 113, 149, 151, 157, 167, 179, 181, 191, 211, 223, 229, 233, 239, 241, 251, 257, 269, 271, 283, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 379, 389, 397, 401, 419, 421, 439, 443, 449, 457, 461, 463
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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This sequence is a variation of the sequence in the reference. However, this sequence should have an infinite number of terms. k=4 in the Pari code.
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REFERENCES
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R. Crandall and C. Pomerance, Prime Numbers A Computational Perspective, Springer Verlag 2002, p. 49, exercise 1.18.
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EXAMPLE
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19*4 = 76, which is one away from 75 and 77 both not prime.
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PROGRAM
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(PARI) primepm3(n, k) = =number of iterations, k = factor { local(x, p1, p2, f1, f2, r); if(k%2, r=2, r=1); for(x=1, n, p1=prime(x); p2=prime(x+1); if(!isprime(p1*k+r)&!isprime(p1*k-r), print1(p1", ") ) ) }
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CROSSREFS
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Sequence in context: A070299 A100460 A073319 this_sequence A076056 A068654 A019384
Adjacent sequences: A120637 A120638 A120639 this_sequence A120641 A120642 A120643
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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), Aug 17 2006
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