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Search: id:A068843
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| A068843 |
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Smallest prime in the first occurrence of a nondecreasing difference for a set of n successive primes. |
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+0
2
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| 37, 11, 17, 2, 1091, 2897, 13451, 448363, 7407287, 34400141, 255030533
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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This is the same as asking for the smallest prime in the first occurrence of a nonnegative second difference for a set of n successive primes.
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EXAMPLE
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a(4) = 2 as the prime set is 2,3,5,7,11 with nondecreasing successive differences 1,2,2,4.
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MATHEMATICA
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(* used to find a(11) *) k = 0; While[p = Select[ Range[ k*10^6, (k + 1)*10^6 + 10^4], PrimeQ[ # ] & ]; l = Length[p]; d1 = Take[p, 1 - l] - Take[p, l - 1]; d2 = Take[d1, 2 - l] - Take[d1, l - 2]; s = Sign[ Sign[d2] + 1]; q = StringPosition[ ToString[s], StringDrop[ StringDrop[ ToString[ Table[1, {10}]], 1], -1]]; q == {}, k++ ]; p[[ (q[[1, 1]] + 1)/3 ]]
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CROSSREFS
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Sequence in context: A057639 A051316 A107812 this_sequence A033357 A093860 A075400
Adjacent sequences: A068840 A068841 A068842 this_sequence A068844 A068845 A068846
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KEYWORD
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nonn,base
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 10 2002
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), May 10 2002 and Dec 08, 2002
a(12) > 2.7*10^9
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