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A155507
Emirps with digits 1 and 9 only.
3
199, 991, 91199, 99119, 111119, 111919, 119191, 191911, 911111, 919111, 991999, 999199, 1191119, 1191191, 1191991, 1911911, 1991911, 9111911, 11111911, 11191991, 11911111, 11919991, 19111991, 19911191, 19919111, 19991911
OFFSET
1,1
COMMENTS
Subsequence of A128390.
LINKS
MATHEMATICA
emrpQ[n_]:=Module[{r=IntegerReverse[n]}, r!=n&&AllTrue[{r, n}, PrimeQ]]; Table[Select[FromDigits/@Tuples[{1, 9}, n], emrpQ], {n, 8}]//Flatten (* Harvey P. Dale, Aug 09 2017 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Lekraj Beedassy, Jan 23 2009
EXTENSIONS
More terms from Sean A. Irvine, Apr 05 2010
STATUS
approved