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Search: id:A055496
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| A055496 |
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a(1) = 2; a(n) is smallest prime > 2*a(n-1). |
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+0
25
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| 2, 5, 11, 23, 47, 97, 197, 397, 797, 1597, 3203, 6421, 12853, 25717, 51437, 102877, 205759, 411527, 823117, 1646237, 3292489, 6584983, 13169977, 26339969, 52679969, 105359939, 210719881, 421439783, 842879579, 1685759167, 3371518343
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Zak Seidov, Table of n, a(n) for n=1..101.
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MAPLE
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A055496 := proc(n) option remember; if n=1 then 2 else nextprime(2*A055496(n-1)); fi; end;
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MATHEMATICA
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NextPrim[n_Integer] := Block[ {k = n + 1}, While[ !PrimeQ[k], k++ ]; Return[k]]; a[1] = 2; a[n_] := NextPrim[ 2*a[n - 1]]; Table[ a[n], {n, 1, 31} ]
a[1]=2; a[n_]:=a[n]=Prime[PrimePi[2*a[n-1]]+1]; Table[a[n], {n, 40}] - Zak Seidov (zakseidov(AT)yahoo.com), Feb 16 2006
<<NumberTheory`NumberTheoryFunctions`; NestList[ NextPrime[2*# ]&, 2, 100] [From Zak Seidov (zakseidov(AT)yahoo.com), Jul 28 2009]
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CROSSREFS
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Cf. A006992.
Values of a(n)-2*a(n-1) in A163469. [From Zak Seidov (zakseidov(AT)yahoo.com), Jul 28 2009]
Cf. also A163963 [From Vladimir Shevelev (shevelev(AT)bgu.ac.il), Aug 07 2009]
Sequence in context: A083329 A153893 A081973 this_sequence A105120 A084403 A055011
Adjacent sequences: A055493 A055494 A055495 this_sequence A055497 A055498 A055499
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Jul 07 2000
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