A155509 -id:A155509 - cp's OEIS frontend

A155507 Emirps with digits 1 and 9 only.

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

Lekraj Beedassy, Jan 23 2009

Subsequence of A128390.

Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

A006567, A128390, A155508, A155509

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 *)

More terms from Sean A. Irvine, Apr 05 2010

A155508 Lesser of emirps (pairs) with digits 1 and 9 only.

Original entry on oeis.org

199, 91199, 111119, 111919, 119191, 991999, 1191119, 1191191, 1191991, 11111911, 11191991, 11919991, 19111991, 91111199, 111111199, 111199199, 191111119, 199991999, 919919999, 1111111999, 1191111991, 1199111191, 1911199999

Offset: 1

Lekraj Beedassy, Jan 23 2009

Harvey P. Dale, Table of n, a(n) for n = 1..660

A006567, A155507, A155509

Flatten[Table[Select[Subsets[Select[FromDigits/@Tuples[{1,9},n],PrimeQ],{2}],AllTrue[#,PrimeQ]&&#[[1]]==IntegerReverse[#[[2]]]&][[All,1]],{n,3,10}]/.{}->Nothing] (* Harvey P. Dale, Aug 21 2020 *)

More terms from Sean A. Irvine, Apr 06 2010

cp's OEIS Frontend

A155507 Emirps with digits 1 and 9 only.

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