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Search: id:A132746
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| A132746 |
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Numbers n such that p(n) + p(n+1) is a perfect power, where p(n) is n-th prime. |
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1
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| 2, 7, 15, 18, 20, 28, 61, 152, 190, 293, 377, 492, 558, 564, 789, 919, 942, 1332, 1768, 2343, 2429, 2693, 2952, 3136, 3720, 3928, 4837, 5421, 5722, 6870, 7347, 8126, 8193, 9465, 9857, 9927, 10410, 10483, 10653, 12685, 13005, 13763, 13955, 16033, 16342
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Cf. A064397 Numbers n such that p(n) + p(n+1) is a square. First terms absent in A064397: 2,18,28,564,1332,3928,12415,13005,16886.
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EXAMPLE
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2 is ok because p(2)+p(3)=3+5=8=2^3 (perfect power)
7 is ok because p(7)+p(8)=17+19=36=6^2 (perfect power)
39867 is ok because p(39867)+p(39868)=478241+478243=956484=978^2 (perfect power).
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PROGRAM
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(PARI) s=[]; for(n=1, 41530, a=prime(n)+prime(n+1); if(ispower(a), s=concat(s, n))); s
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CROSSREFS
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Cf. A064397.
Sequence in context: A088824 A034903 A070898 this_sequence A167543 A029888 A005449
Adjacent sequences: A132743 A132744 A132745 this_sequence A132747 A132748 A132749
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Nov 17 2007
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