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Search: id:A073698
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| A073698 |
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a(n) is smallest prime not already in the sequence such that the sum of the first n terms is an n-th power. |
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+0
4
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| 2, 7, 503, 113, 7151, 109873, 162287, 2251875110689, 1423309560546093919, 1831931738588396657, 266306005917953213327, 13573982207668041076860262513, 4485809513902758532742979512207
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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Sum of two terms 2+7 = 9 = 3^2. Sum of three terms 2+7+503 = 512 = 8^3.
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MATHEMATICA
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a[n_] := a[n]=Module[{sm, i}, sm=Sum[a[i], {i, 1, n-1}]; For[k=Ceiling[(sm+2)^(1/n)], !ProvablePrimeQ[k^n-sm]||MemberQ[a/@Range[n-1], k^n-sm], k++, Null]; k^n-sm] (* First do <<NumberTheory`PrimeQ` *)
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CROSSREFS
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Cf. A093927, A093928, A093929, A093355.
Sequence in context: A081505 A110386 A027732 this_sequence A073860 A093926 A095304
Adjacent sequences: A073695 A073696 A073697 this_sequence A073699 A073700 A073701
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Aug 12 2002
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EXTENSIONS
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Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Dec 02 2002
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