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A097527
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Least k such that k*P(n)#-P(n+3) and k*P(n)#+P(n+3) are both primes with P(i)=i-th prime and P(i)#=i-th primorial.
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0
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5, 3, 1, 1, 3, 2, 12, 2, 2, 29, 69, 33, 15, 9, 28, 8, 111, 121, 55, 92, 4, 269, 89, 138, 57, 102, 39, 113, 81, 79, 155, 85, 647, 482, 369, 29, 295, 81, 88, 1, 14, 229, 33, 350, 29, 85, 738, 143, 304, 217, 805, 2421, 166, 370, 616, 111, 621, 543, 160, 200, 1825, 909, 256
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OFFSET
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1,1
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LINKS
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EXAMPLE
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2*3*5 - 13 = 17, prime; 2*3*5 + 13 = 43, prime; so for n=3, k=1.
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MATHEMATICA
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Primorial[n_] := Product[ Prime[i], {i, n}]; f[n_] := Block[{k = 1, p = Primorial[n], q = Prime[n + 3]}, While[k*p - q < 2 || !PrimeQ[k*p - q] || !PrimeQ[k*p + q], k++ ]; k]; Table[ f[n], {n, 63}] (* Robert G. Wilson v, Aug 31 2004 *)
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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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EXTENSIONS
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STATUS
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approved
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