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A039999
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Number of permutations of digits of n which denote primes.
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14
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0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 2, 1, 0, 1, 2, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 2, 1, 0, 1, 1, 0, 2, 1, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 2, 0, 2, 1, 0, 1, 0, 0, 2, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 2, 1, 0, 0, 2, 0, 3, 2, 0
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OFFSET
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1,13
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COMMENTS
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Consider all k! permutations of digits of a k-digit number n, discard initial zeros, count distinct primes.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..10000
C. Hilliard, PARI program.
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EXAMPLE
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a(20)=1, since from {02, 20} we get {2,20} and only 2 is prime. From 107 we get 4 primes: (0)17, (0)71, 107 and 701; so a(107) = 4.
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MATHEMATICA
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Table[Count[FromDigits/@Permutations[IntegerDigits[n]], _?PrimeQ], {n, 110}] (* From Harvey P. Dale, June 26 2011 *)
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PROG
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(PARI) for(x=1, 400, print1(permprime(x), ", ")) /* for definition of function permprime cf. link */ [From Cino Hilliard (hillcino368(AT)hotmail.com), Jun 07 2009]
(MAGMA) [ #[ s: s in Seqset([ Seqint([m(p[i]):i in [1..#x] ], 10): p in Permutations(Seqset(x)) ]) | IsPrime(s) ] where m is map< x->y | [<x[i], y[i]>:i in [1..#x] ] > where x is [1..#y] where y is Intseq(n, 10): n in [1..120] ]; [From Klaus Brockhaus, Jun 15 2009]
(Haskell)
import Data.List (permutations, nub)
a039999 n = length $ filter ((== 1) . a010051)
(map read (nub $ permutations $ show n) :: [Integer])
-- Reinhard Zumkeller, Feb 07 2011
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CROSSREFS
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Cf. A046810.
Sequence in context: A170958 A178651 A046810 * A069842 A083056 A061896
Adjacent sequences: A039996 A039997 A039998 * A040000 A040001 A040002
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KEYWORD
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nonn,base,nice,easy
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AUTHOR
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David W. Wilson
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EXTENSIONS
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Contribution of C. Hilliard edited by Klaus Brockhaus, Jun 15 2009
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STATUS
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approved
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