

A090715


Primes which are also prime if their base 31 representation is interpreted as a base 10 number.


1



2, 3, 5, 7, 71, 127, 131, 193, 251, 257, 1061, 1063, 1117, 1123, 1181, 1187, 1249, 1987, 1993, 2111, 2917, 3041, 3109, 3169, 3853, 3907, 4099, 4967, 5023, 5087, 5897, 5953, 6823, 6829, 6883, 6947, 7013, 7753, 7757, 7759, 7877, 7937, 8681, 8689, 8807, 8867
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OFFSET

1,1


LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000


EXAMPLE

71 is prime; in base 31 it is written "29" and the base 10 number 29 is also prime.


MATHEMATICA

b31Q[n_]:=Module[{idn31=IntegerDigits[n, 31]}, Max[idn31] <10&&PrimeQ[FromDigits[idn31]]]; Select[Prime[Range [PrimePi[9000]]], b31Q] (* Harvey P. Dale, Mar 19 2011 *)


CROSSREFS

Sequence in context: A171029 A241723 A090717 * A029976 A074310 A264576
Adjacent sequences: A090712 A090713 A090714 * A090716 A090717 A090718


KEYWORD

base,nonn


AUTHOR

Cino Hilliard, Jan 18 2004


EXTENSIONS

Edited by Jens Kruse Andersen, May 04 2008
Changed offset from 2 to 1 by Vincenzo Librandi, Apr 18 2013


STATUS

approved



