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A134996 Dihedral calculator primes: p, p upside down, p in a mirror, p upside-down-and-in-a-mirror are all primes. 3
2, 5, 11, 101, 181, 1181, 1811, 18181, 108881, 110881, 118081, 120121, 121021, 121151, 150151, 151051, 151121, 180181, 180811, 181081, 188011, 188801, 1008001, 1022201, 1028011, 1055501, 1058011, 1082801, 1085801, 1088081 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..30.

C. K. Caldwell, The Prime Glossary, Dihedral Prime

Eric Weisstein's World of Mathematics, Dihedral Prime.

EXAMPLE

120121 is such a number because 120121, 121021 (upside down), 151051 (mirror) and 150151 are all prime. (This is the smallest one in which all four numbers are distinct.)

CROSSREFS

Cf. A038136, A048660, A048662.

Sequence in context: A213073 A018847 A178318 * A134998 A078790 A158999

Adjacent sequences:  A134993 A134994 A134995 * A134997 A134998 A134999

KEYWORD

nonn,base,nice

AUTHOR

Mike Keith (domnei(AT)aol.com)

EXTENSIONS

5 added by Patrick Capelle, Feb 06 2008

STATUS

approved

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Last modified September 21 14:10 EDT 2014. Contains 247026 sequences.