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Search: id:A088621
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| A088621 |
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a(n) = smallest prime which is a concatenation of 1, n, n^2, n^3, ... n^k for some k, or 0 if no such prime exists. |
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+0
1
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| 11, 0, 13, 0, 0, 0, 17, 0, 19, 0, 111121, 0, 113, 0, 0, 0
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(2n)=a(5n)=0. Next term a(17) has 176 digits (k=16) and is too large to include in sequence. a(19), if it exists, has k>100. - Ray Chandler (rayjchandler(AT)sbcglobal.net), Oct 18 2003
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EXAMPLE
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a(11) = 111121 which is a concatenation of 1, 11 and 121. value of k = 2.
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MATHEMATICA
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f[n_] := Block[{k = FromDigits[Join[{1}, IntegerDigits[n]]], e = 1}, While[ !PrimeQ[k], e++; k = FromDigits[Join[IntegerDigits[k], IntegerDigits[n^e]]]]; k]; g[n_] := If[ Mod[n, 10] == 1 || Mod[n, 10] == 3 || Mod[n, 10] == 7 || Mod[n, 10] == 9, f[n], 0]; Table[ g[n], {n, 1, 17}] (from Robert G. Wilson v)
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CROSSREFS
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Cf. A088619, A068702.
Sequence in context: A003621 A055963 A127805 this_sequence A088623 A167166 A147765
Adjacent sequences: A088618 A088619 A088620 this_sequence A088622 A088623 A088624
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KEYWORD
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base,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Oct 17 2003
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EXTENSIONS
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The next term is too large to include. - Robert G. Wilson v, Oct 19 2003
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