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A107666 Primes with semiprime digits (digits 4, 6, 9 only). 9

%I

%S 449,499,4649,4969,4999,6449,6469,6949,9649,9949,44449,44699,46499,

%T 46649,49499,49669,49999,64499,64969,66449,66499,66949,69499,94649,

%U 94949,94999,96469,99469,444449,444469,444649,446969,449699,464699,464999,466649,469649,469969

%N Primes with semiprime digits (digits 4, 6, 9 only).

%C Intersection of A000040 and A107665. - _K. D. Bajpai_, Sep 08 2014

%H K. D. Bajpai, <a href="/A107666/b107666.txt">Table of n, a(n) for n = 1..2069</a>

%e From _K. D. Bajpai_, Sep 08 2014: (Start)

%e 4649 is a term because it is a prime having only semiprime digits 4, 6 and 9.

%e 6469 is a term because it is a prime having only semiprime digits 4, 6 and 9.

%e 449 is the smallest prime comprising only semiprime digits 4, 6 or 9.

%e (End)

%p N:= 4: Dgts:= {4, 6, 9}: A:= NULL:

%p for d from 1 to N do

%p K:= combinat[cartprod]([Dgts minus {0}, Dgts $(d-1)]);

%p while not K[finished] do L:= K[nextvalue](); x:= add(L[i]*10^(d-i), i=1..d);

%p if isprime(x) then A:= A, x fi od od: A; # _K. D. Bajpai_, Sep 08 2014

%t Select[Prime[Range[50000]], Intersection[IntegerDigits[#], {0, 1, 2, 3, 5, 7, 8}] == {} &] (* _K. D. Bajpai_, Sep 08 2014 *)

%Y Cf. A107665 (numbers with semiprime digits), A001358 (semiprimes), A051416 (primes whose digits are all composite), A020466 (primes with digits 4 and 9 only), A093402 (primes of form 44...9), A093945 (primes of form 499...).

%Y Cf. A107342, A111494, A111496, A111697.

%K base,nonn

%O 1,1

%A _Rick L. Shepherd_, May 19 2005

%E a(35) to a(38) from _K. D. Bajpai_, Sep 08 2014

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Last modified July 13 13:48 EDT 2020. Contains 335688 sequences. (Running on oeis4.)