Search: id:A039999
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%I A039999
%S A039999 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,
%T A039999 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,
%U A039999 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
%N A039999 Number of permutations of digits of n which denote primes.
%C A039999 Consider all k! permutations of digits of a k-digit number n, discard 
               initial zeros, count distinct primes.
%H A039999 T. D. Noe, <a href="b039999.txt">Table of n, a(n) for n=1..10000</a>
%H A039999 C. Hilliard, <a href="a039999.txt">PARI program.</a>
%e A039999 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.
%o A039999 (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]
%o A039999 (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]
%Y A039999 Cf. A046810.
%Y A039999 Sequence in context: A063933 A085860 A046810 this_sequence A069842 A083056 
               A061896
%Y A039999 Adjacent sequences: A039996 A039997 A039998 this_sequence A040000 A040001 
               A040002
%K A039999 nonn,base,nice,easy
%O A039999 1,13
%A A039999 Dave Wilson
%E A039999 Contribution of C. Hilliard edited by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), 
               Jun 15 2009

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