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A048890 Primes that yield a different prime when rotated by 180 degrees. 7
19, 61, 109, 199, 601, 661, 1019, 1061, 1091, 1109, 1181, 1601, 1609, 1669, 1699, 1811, 1901, 1999, 6011, 6091, 6101, 6199, 6619, 6661, 6689, 6691, 6899, 6991, 10061, 10069, 10091, 10691, 10861, 10909, 11069, 11681, 11909, 16001, 16619, 16661 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Also called invertible primes. [Lekraj Beedassy, Jan 03 2009]

LINKS

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

C. K. Caldwell, The Prime Glossary, strobogrammatic [Lekraj Beedassy, Jan 03 2009]

MATHEMATICA

lst = {}; fQ[n_] := Block[{allset = {0, 1, 6, 8, 9}, id = IntegerDigits@n}, rid = Reverse[id /. {6 -> 9, 9 -> 6}]; Union@ Join[id, allset] == allset && PrimeQ@ FromDigits@ rid && rid != id]; Do[ If[ PrimeQ@n && fQ@n, AppendTo[lst, n]], {n, 16900}]; lst (* Robert G. Wilson v, Feb 27 2007 *)

PROG

(Haskell)

import Data.List (unfoldr)

a048890 n = a048890_list !! (n-1)

a048890_list = filter f a000040_list where

   f x = all (`elem` [0, 1, 6, 8, 9]) ds && x' /= x && a010051 x' == 1

     where x' = foldl c 0 ds

           c v 6 = 10*v + 9; c v 9 = 10*v + 6; c v d = 10*v + d

           ds = unfoldr d x

           d z = if z == 0 then Nothing else Just $ swap $ divMod z 10

-- Reinhard Zumkeller, Nov 18 2011

CROSSREFS

Cf. A007597, A006567, A046732.

Sequence in context: A158521 A141897 A031384 * A127854 A092327 A139498

Adjacent sequences:  A048887 A048888 A048889 * A048891 A048892 A048893

KEYWORD

base,nonn,easy,nice

AUTHOR

G. L. Honaker, Jr.

EXTENSIONS

Better definition and more terms from Robert G. Wilson v, Feb 27 2007

STATUS

approved

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Last modified January 22 12:13 EST 2019. Contains 319363 sequences. (Running on oeis4.)