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A088092 Palindromic primes p such that if each digit d is replaced by 10-d then the resulting palindrome is also a prime. 1
3, 5, 7, 181, 191, 313, 353, 383, 727, 757, 797, 919, 929, 12421, 12721, 14341, 17971, 32323, 78787, 93139, 96769, 98389, 98689, 1129211, 1145411, 1153511, 1175711, 1178711, 1183811, 1221221, 1273721, 1328231, 1486841, 1633361, 1824281 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Digit 0 is not allowed. - Robert Israel, Sep 14 2020

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

181 is a member as replacing 1 by 10-1 = 9 and 8 by 10-8 =2 gives 929 which is also a prime.

MAPLE

R:= NULL: count:= 0:

for d from 1 by 2 while count < 100 do

  m:= ceil(d/2);

  for r from 0 to 9^m-1 do

    L:= convert(9^m+r, base, 9)[1..m] + [1$m];

    L:= [ seq(L[-i], i=1..m-1), op(L)];

    x:= add(L[i]*10^(i-1), i=1..d);

    if isprime(x) and isprime((10^d-1)*10/9-x) then R:= R, x; count:= count+1

      fi

od od:

R; # Robert Israel, Sep 14 2020

CROSSREFS

Cf. A002385 (palindromic primes).

Sequence in context: A128344 A259385 A114366 * A174271 A211678 A082756

Adjacent sequences:  A088089 A088090 A088091 * A088093 A088094 A088095

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Sep 23 2003

EXTENSIONS

Corrected and extended by David Wasserman, Jul 18 2005

STATUS

approved

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Last modified December 6 18:16 EST 2021. Contains 349567 sequences. (Running on oeis4.)