

A209620


Emirps that become their own reversals when rotated through 180 degrees (including on calculator display).


0



1021, 1151, 1181, 1201, 1511, 1811, 10151, 11551, 15101, 15511, 100511, 101281, 102181, 102551, 105211, 105251, 108881, 110051, 110221, 110281, 110881, 111211, 111821, 112111, 112181, 112501, 115001, 115021, 118081, 120121, 120511, 121021, 121151, 122011
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OFFSET

1,1


COMMENTS

Such emirps have end digits 1 and use only digits 0, 1, 2, 5, 8, and the sequence naturally includes A155512, the emirps with only digits 0 and 1.


LINKS



EXAMPLE

1181 of this sequence, for instance, belongs to the emirp pair (1181, 1811), where each member is a 180degree rotation of the other; similarly for the term 112501 of this sequence, that belongs to the emirp pair (105211, 112501) and which, displayed on a calculator and turned upsidedown, becomes its own reversal.


MATHEMATICA

t1 = {0, 1, 2, 5, 8}; okQ[n_] := Module[{d = IntegerDigits[n], r}, r = Reverse[d]; r != d && Complement[d, t1] == {} && PrimeQ[FromDigits[r]]]; Select[Prime[Range[100000]], okQ] (* T. D. Noe, Apr 24 2012 *)


CROSSREFS



KEYWORD

nonn,base


AUTHOR



STATUS

approved



