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A125589
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Smallest n-digit base-10 deletable prime.
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1
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2, 13, 103, 1013, 10039, 100103, 1000193, 10000931, 100001903, 1000003957, 10000003957, 100000013957, 1000000030957, 10000000301957, 100000000730957, 1000000000730957, 10000000003632979, 100000000007309357
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OFFSET
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1,1
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COMMENTS
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A prime p is a base-b deletable prime if when written in base b it has the property that removing some digit leaves either the empty string or another deletable prime. "Digit" means digit in base b.
Deleting a digit cannot leave any leading zeros in the new string. For example, deleting the 2 in 2003 to obtain 003 is not allowed.
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LINKS
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MATHEMATICA
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b = 10; a = {2}; d = {2, 3, 5, 7};
For[n = 2, n <= 6, n++,
found = False;
p = Select[Range[b^(n - 1), b^n - 1], PrimeQ[#] &];
For[i = 1, i <= Length[p], i++,
c = IntegerDigits[p[[i]], b];
For[j = 1, j <= n, j++,
t = Delete[c, j];
If[t[[1]] == 0, Continue[]];
If[MemberQ[d, FromDigits[t, b]], AppendTo[d, p[[i]]];
If[! found , AppendTo[a, p[[i]]]]; found = True; Break[]]];
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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