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A261820
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Minimal nested palindromic primes with seed 111.
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2
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111, 1311131, 113111311, 91131113119, 9911311131199, 12991131113119921, 771299113111311992177, 1077129911311131199217701, 11107712991131113119921770111, 101110771299113111311992177011101, 107101110771299113111311992177011101701
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OFFSET
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1,1
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COMMENTS
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Let s be a palindrome and put a(1) = s. Let a(2) be the least palindromic prime having s in the middle; for n > 2, let a(n) be the least palindromic prime having a(n-1) in the middle. Then (a(n)) is the sequence of minimal nested palindromic primes with seed s.
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LINKS
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EXAMPLE
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As a triangle:
111
1311131
113111311
91131113119
9911311131199
12991131113119921
771299113111311992177
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MATHEMATICA
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s0 = "111"; s = {ToExpression[s0]}; Do[NestWhile[# + 1 &, 1, ! PrimeQ[tmp = FromDigits[Join[#, IntegerDigits[Last[s], 10, Max[StringLength[s0], Length[IntegerDigits[Last[s]]]]], Reverse[#]]&[IntegerDigits[#]]]] &]; AppendTo[s, tmp], {10}]; s0 <> ", " <> StringTake[ToString[Rest[s]], {2, -2}]
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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