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Search: id:A064397
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| A064397 |
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Numbers n such that p(n) + p(n+1) is a square. p(n) is n-th prime. |
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+0
5
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| 7, 15, 20, 61, 152, 190, 293, 377, 492, 558, 789, 919, 942, 1768, 2343, 2429, 2693, 2952, 3136, 3720, 4837, 5421, 5722, 6870, 7347, 8126, 8193, 9465, 9857, 9927, 10410, 10483, 10653, 12685, 13763, 13955, 16033, 16342, 17859, 18367, 18474
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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n=15: prime(15) = 47 and prime(16) = 53, 47+53 = 100 = 10^2.
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MATHEMATICA
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lst={}; Do[p1=Prime[n]; p2=Prime[n+1]; q=(p1+p2)^0.5; If[q==IntegerPart[q], AppendTo[lst, n]], {n, 1, 9!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Sep 02 2008]
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PROGRAM
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(PARI) j=[]; for(n=1, 30000, x=prime(n)+prime(n+1); if(issquare(x), j=concat(j, n))); j
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CROSSREFS
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Sequence in context: A138641 A115783 A141014 this_sequence A014659 A053354 A022552
Adjacent sequences: A064394 A064395 A064396 this_sequence A064398 A064399 A064400
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KEYWORD
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nonn
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AUTHOR
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Jason Earls (zevi_35711(AT)yahoo.com), Sep 29 2001
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