A246870 Lesser of the Gridgeman pairs in base 2 in increasing order: pairs of primes palindromic in base 2 which differ only in their middle digits.

5, 22541, 296201, 360461, 499151, 514271, 1071937, 1096609, 1298809, 1347877, 1458253, 4404833, 5497829, 5694389, 6824459, 7010219, 7168859, 7267259, 8102639, 17629537, 19525417, 21884773, 23330893, 24364957, 24440413, 24538333, 24735037, 25445443, 28493467

Offset

1,1

Links

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

Prime Curios!, 181

Example

22541 and 22669 are primes with binary representations 101100000001101 and 101100010001101 respectively.

Prog

(Python)
from sympy import isprime
A246870 = []
for n in range(1, 2**17):
....s1 = bin(n)[2:]
....s2 = s1[::-1]
....p1, p2 = int(s1+'0'+s2, base), int(s1+'1'+s2, base)
....if isprime(p1) and isprime(p2):
........A246870.append(p1)
A246870 = sorted(A246870)

Crossrefs

Cf. A246488, A246871, A246872.

Sequence in context: A191940 A055380 A201002 * A193366 A347934 A228547

Adjacent sequences: A246867 A246868 A246869 * A246871 A246872 A246873

Keyword

nonn,base

Author

Chai Wah Wu, Sep 06 2014

Status

approved