A179507 Smallest emirp with a base-10 digit set of {0,1,..,n}.
10011101, 1021, 10321, 102043, 1015423, 10224563, 10243657, 1012356487, 10124389567
Offset: 1
Extensions
Definition rephrased by R. J. Mathar, Jul 20 2010
This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
a(0) = 20 as there are twenty primes created when concatenating the integer arrangements of 0,1,2,3,4. They are 1423, 2143, 2341, 4231, 10243, 12043, 20143, 20341, 20431, 23041, 24103, 30241, 32401, 40123, 40213, 40231, 41023, 41203, 42013, 43201. a(1) = 3202. The smallest prime created using integers 0..7 is 1234657 while the largest is 76540231. a(2) = 2056675. The smallest prime created using integers 0..10 is 10123457689 while the largest is 987654310021.
Table[Count[FromDigits /@ Flatten /@ IntegerDigits /@ Permutations[Range[0, 3 n + 4]], ?PrimeQ], {n, 0, 2}] (* _Robert Price, Sep 16 2020 *) (* OR, if the above runs low on memory to store all the Permutations at once... *) Table[p0 = Range[0, 3n+4]; p = NextPermutation[p0]; c = 0; While[p != p0, If[PrimeQ[FromDigits[Flatten[IntegerDigits /@ p]]], c++]; p = NextPermutation[p]]; c, {n, 0, 2}] (* Robert Price, Sep 16 2020 *)
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