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 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 (list; graph; refs; listen; history; text; internal format)
 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 !! (n-1) 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: A286453 A309375 A018847 * A134996 A134998 A078790 Adjacent sequences:  A178315 A178316 A178317 * A178319 A178320 A178321 KEYWORD nonn,base AUTHOR David Nacin, May 24 2010 STATUS approved

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Last modified April 13 15:23 EDT 2021. Contains 342936 sequences. (Running on oeis4.)