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Search: id:A157480
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| A157480 |
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The differences between the primes and the next squares are prime. |
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+0
1
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| 2, 13, 11, 2, 5, 3, 19, 17, 2, 7, 5, 107, 23, 101, 2, 11, 5, 3, 257, 29, 71, 2, 17, 11, 3, 43, 41, 37, 467, 31, 17, 13, 7, 5, 47, 173, 167, 1601, 2, 23, 17, 719, 5, 3, 59, 701, 113, 2, 29, 347, 23, 17, 83, 5, 67, 61, 131, 53, 47, 43, 41, 31, 17, 13, 11, 7, 569, 239, 53, 227, 47, 2
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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It is appropriate to add a counter to the program to ensure a square is found
for all primes <= n. Here we set n^2 as the difference upper bound. This
appears to be high but with no loss in efficiecy since we break out of the
loop when the first square is found. This partial listing was generated for
primes < 1000. Notice that 1601 would have been missed had we set the
difference upper bound to 1000.
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EXAMPLE
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The difference between prime 3 and the square 16 is 13 which is prime and in
the sequence.
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PROGRAM
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(PARI) g(n)= c=0; forprime(x=2, n, for(k=1, n^2, if(issquare(x+k)&&isprime(k),
print1(k", "); c++; break))); c
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CROSSREFS
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Sequence in context: A128155 A158088 A124869 this_sequence A065584 A153651 A075032
Adjacent sequences: A157477 A157478 A157479 this_sequence A157481 A157482 A157483
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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), Mar 01 2009
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