A246871 Lesser of Gridgeman pairs in base 8 in increasing order: pairs of primes palindromic in base 8 which differ only in their middle digits by a difference of 1.

2, 89, 479, 12547, 14563, 15667, 28807, 30367, 31663, 32119, 296969, 311561, 318281, 328721, 383321, 409889, 422369, 452009, 490481, 511289, 792131, 936227, 951851, 1345037, 1366349, 1444901, 1505261, 1543229, 1852679, 1861511, 1865159, 1871951, 1898447

Offset

1,1

Links

Chai Wah Wu, Table of n, a(n) for n = 1..1000

Prime Curios!, 181

Example

12547 and 12611 are 2 primes with base 8 representation 30403 and 30503 respectively.

Prog

(Python)
from gmpy2 import digits
from sympy import isprime
A246871 = [2]
for n in range(1, 8**5):
....s1 = digits(n, 8)
....s2 = s1[::-1]
....for m in range(7):
........p1, p2 = int(s1+str(m)+s2, 8), int(s1+str(m+1)+s2, 8)
........if isprime(p1) and isprime(p2):
............A246871.append(p1)
A246871 = sorted(A246871)

Crossrefs

Cf. A246488, A246870, A246872.

Sequence in context: A023302 A041967 A226768 * A024239 A338734 A309994

Adjacent sequences: A246868 A246869 A246870 * A246872 A246873 A246874

Keyword

nonn,base

Author

Chai Wah Wu, Sep 06 2014

Status

approved