A082439 Palindromic primes with middle digit 3.

3, 131, 10301, 11311, 13331, 14341, 16361, 19391, 32323, 35353, 71317, 76367, 77377, 79397, 94349, 97379, 98389, 1003001, 1043401, 1093901, 1123211, 1153511, 1163611, 1183811, 1193911, 1243421, 1253521, 1273721, 1303031, 1333331, 1343431, 1363631, 1463641

Offset

1,1

Comments

Palindromic primes in the usual sense (i.e. A002385, not A007500).

Links

Chai Wah Wu, Table of n, a(n) for n = 1..10000

Maple

revdigs := proc(n)
  local L, nL, j;
  L:= convert(n, base, 10);
  nL:= nops(L);
  add(L[i]*10^(nL-i), i=1..nL);
end:
select(isprime, [3, seq(seq(n*10^(d+1)+3*10^d + revdigs(n), n=10^(d-1) .. 10^d-1), d= 1..4)]); # Robert Israel, Nov 11 2015

Mathematica

ppmd3Q[n_]:=Module[{idn=IntegerDigits[n], len}, len=Length[idn]; OddQ[len] && idn==Reverse[idn]&&idn[[(len+1)/2]]==3]; Select[Prime[ Range[ 120000]], ppmd3Q] (* Harvey P. Dale, Feb 12 2015 *)

Prog

(Magma) [ p: p in PrimesUpTo(200000000) | IsOdd(d) and D[(d+1) div 2] eq 3 and D eq Reverse(D) where d is #D where D is Intseq(p) ]; // Vincenzo Librandi, Apr 12 2011
(Python)
from gmpy2 import is_prime
A082439_list = [3]
for i in range(1, 10**6):
    s = str(i)
    n = int(s+'3'+s[::-1])
    if is_prime(n):
        A082439_list.append(n) # Chai Wah Wu, Nov 11 2015

Crossrefs

Cf. A002385.

Sequence in context: A139943 A005175 A347985 * A082622 A332113 A075597

Adjacent sequences: A082436 A082437 A082438 * A082440 A082441 A082442

Keyword

nonn,base

Author

Lekraj Beedassy, Apr 25 2003

Extensions

Added a(4), a(13), a(14), a(28) by Vincenzo Librandi, Apr 12 2011

Status

approved