

A178318


Primes which remain prime after reflection across a vertical line through the middle of the number (numbers are written as digital clock style numerals).


1



2, 5, 11, 101, 181, 1051, 1181, 1201, 1811, 10151, 11251, 11551, 12101, 12211, 12511, 15121, 18181, 100151, 100501, 101501, 101581, 102001, 102101, 102181, 102551, 105211, 105251, 108881, 110051, 110581, 110881, 111521, 111581, 115021, 115201
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OFFSET

1,1


COMMENTS

Apart from first two terms: subsequence of A208259.  Reinhard Zumkeller, Jul 16 2014


LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000


EXAMPLE

For example 1051 becomes 1201 under this reflection and since these are both prime, these number are part of the sequence. Note that a number must be composed only of the digits 0,1,2,5,8 to qualify.


PROG

(Haskell)
import Data.List (intersect, genericIndex)
a178318 n = a178318_list !! (n1)
a178318_list = 2 : 5 : filter f a062332_list where
f p = null (show p `intersect` "34679") && a010051' (r 0 p) == 1
r y 0 = y
r y x = r (10 * y + genericIndex [0, 1, 5, 0, 0, 2, 0, 0, 8, 0] d) x'
where (x', d) = divMod x 10
 Reinhard Zumkeller, Jul 16 2014


CROSSREFS

Cf. A125308, A178317.
Cf. A010051, A004086, A208259, A062332.
Sequence in context: A213073 A267527 A018847 * A134996 A134998 A078790
Adjacent sequences: A178315 A178316 A178317 * A178319 A178320 A178321


KEYWORD

nonn,base


AUTHOR

David Nacin, May 24 2010


STATUS

approved



