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A107666 Primes with semiprime digits (digits 4, 6, 9 only). 9
449, 499, 4649, 4969, 4999, 6449, 6469, 6949, 9649, 9949, 44449, 44699, 46499, 46649, 49499, 49669, 49999, 64499, 64969, 66449, 66499, 66949, 69499, 94649, 94949, 94999, 96469, 99469, 444449, 444469, 444649, 446969, 449699, 464699, 464999, 466649, 469649, 469969 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Intersection of A000040 and A107665. - K. D. Bajpai, Sep 08 2014

LINKS

K. D. Bajpai, Table of n, a(n) for n = 1..2069

EXAMPLE

From K. D. Bajpai, Sep 08 2014: (Start)

4649 is in the sequence because it is prime having only semiprime digits 4, 6 and 9.

6469 is in the sequence because it is prime having only semiprime digits 4, 6 and 9.

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

(End)

MAPLE

N:= 4:  Dgts:= {4, 6, 9}:  A:= NULL:

for d from 1 to N do

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

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

if isprime(x) then A:= A, x fi od od: A;  # K. D. Bajpai, Sep 08 2014

MATHEMATICA

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

CROSSREFS

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...).

Cf. A107342, A111494, A111496, A111697.

Sequence in context: A174154 A071104 A087700 * A020466 A142420 A105376

Adjacent sequences:  A107663 A107664 A107665 * A107667 A107668 A107669

KEYWORD

base,nonn

AUTHOR

Rick L. Shepherd, May 19 2005

EXTENSIONS

a(35) to a(38) from K. D. Bajpai, Sep 08 2014

STATUS

approved

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Last modified December 9 21:41 EST 2016. Contains 278987 sequences.