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Search: id:A096937
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| A096937 |
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Least k such that k*P(n)#/2 - 2 and k*P(n)#/2 + 2 are both primes, where P(i)= i-th prime, P(i)# = i-th primorial. |
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+0
1
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| 5, 3, 1, 1, 3, 1, 3, 41, 27, 3, 1, 171, 97, 19, 35, 13, 217, 57, 79, 133, 41, 219, 85, 43, 477, 205, 35, 455, 635, 275, 2081, 33, 513, 671, 427, 177, 997, 2671, 601, 123, 525, 1139, 411, 479, 363, 1311, 4685, 109, 159, 3367, 2761, 257, 161, 137, 49, 393, 3553, 1807
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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1*2*3*5*7/2 - 2 = 103 1*2*3*5*7/2 + 2 = 107, 103 and 107 are both primes so for n=4 k=1
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MATHEMATICA
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Primorial[n_] := Product[Prime[i], {i, 1, n}]; f[n_] := Block[{p = Primorial[n]/2, k = 1}, While[ !PrimeQ[k*p - 2] || !PrimeQ[k*p + 2], k++ ]; k]; Table[ f[n], {n, 50}] (from Robert G. Wilson v Aug 19 2004)
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CROSSREFS
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Cf. A060256.
Sequence in context: A132199 A111142 A094853 this_sequence A097527 A132400 A063268
Adjacent sequences: A096934 A096935 A096936 this_sequence A096938 A096939 A096940
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KEYWORD
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nonn
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AUTHOR
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Pierre CAMI (pierrecami(AT)tele2.fr), Aug 18 2004
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 19 2004
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