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A065849
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Let u be any string of n digits from {0,...,7}; let f(u) = number of distinct primes, not beginning with 0, formed by permuting the digits of u; then a(n) = max_u f(u).
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10
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1, 2, 3, 11, 23, 113, 425, 1912, 11872, 57918, 303157, 1757094
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OFFSET
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1,2
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LINKS
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Table of n, a(n) for n=1..12.
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EXAMPLE
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a(2)=2 because 15 and 51 (written in base 8) are primes (13 and 41).
a(3)=3 because 531, 351 and 513 (in base 8) are primes (107, 233, 331), or 145, 415 and 541 (in base 8) are primes (101, 269, 353), or 147, 417 and 471 are primes (103, 271, 313) etc. R. J. Mathar, Apr 23 2016
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MATHEMATICA
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c[x_] := Module[{},
Length[Select[Permutations[x],
First[#] != 0 && PrimeQ[FromDigits[#, 8]] &]]];
A065849[n_] := Module[{i},
Return[Max[Map[c, DeleteDuplicatesBy[Tuples[Range[0, 7], n],
Table[Count[#, i], {i, 0, 7}] &]]]]];
Table[A065849[n], {n, 1, 7}] (* Robert Price, Mar 30 2019 *)
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CROSSREFS
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Cf. A065843, A065844, A065845, A065846, A065847, A065848, A065850, A065851, A065852, A065853
Sequence in context: A074496 A292817 A292112 * A136402 A137811 A041955
Adjacent sequences: A065846 A065847 A065848 * A065850 A065851 A065852
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KEYWORD
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base,more,nonn
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AUTHOR
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Sascha Kurz, Nov 24 2001
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EXTENSIONS
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2 more terms from Sean A. Irvine, Sep 06 2009
Definition corrected by David A. Corneth, Apr 23 2016
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STATUS
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approved
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