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A242751 Semiprimes having only holey digits (0,4,6,8,9). 1
4, 6, 9, 46, 49, 69, 86, 94, 446, 466, 469, 489, 649, 669, 689, 694, 698, 699, 849, 866, 869, 886, 889, 898, 899, 949, 989, 998, 4006, 4009, 4069, 4406, 4449, 4469, 4486, 4489, 4499, 4609, 4666, 4694, 4699, 4846, 4849, 4894, 4946, 4989, 6009, 6046, 6049, 6098 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
4609 = 11 * 419 is semiprime and has only holey digits 4, 6, 0 and 9. Hence it is in the sequence.
4849 = 13 * 373 is semiprime and has only holey digits 4, 8, 4 and 9. Hence it is in the sequence.
MATHEMATICA
c = 0; Do[a = PrimeOmega[n]; If[a==2&& Intersection[IntegerDigits[n], {1, 2, 3, 5, 7}]=={}, c++; Print[c, " ", n]], {n, 2*10^7}]
Select[FromDigits/@Tuples[{0, 4, 6, 8, 9}, 4], PrimeOmega[#]==2&] (* Harvey P. Dale, Sep 08 2017 *)
CROSSREFS
Sequence in context: A257652 A107665 A085733 * A107342 A086698 A317248
KEYWORD
nonn,base
AUTHOR
K. D. Bajpai, May 21 2014
STATUS
approved

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)