A084837 Palindromic primes with nonincreasing digits up to the middle and then nondecreasing.

2, 3, 5, 7, 11, 101, 313, 727, 757, 919, 929, 31013, 72227, 73037, 73237, 74047, 75557, 76367, 76667, 77377, 77477, 91019, 93139, 93239, 94049, 94349, 96269, 96469, 97379, 97579, 98389, 98689, 3211123, 3222223, 3310133, 3321233, 3331333, 7100017, 7300037, 7310137

Offset: 1

Author

Patrick De Geest, Jun 07 2003

Keywords

• nonn
• base

Links

• Michael S. Branicky, Table of n, a(n) for n = 1..10000
• Patrick De Geest, World of Palindromic Primes

Crossrefs

Cf. A084836, A062351, A062352.

Programs

Python

from sympy import isprime
from itertools import count, islice, combinations_with_replacement as mc
def agen(): # generator of terms
    yield from (2, 3, 5, 7, 11)
    for d in count(2):
        nind = (int("".join(m+m[:-1][::-1])) for m in mc("9876543210", d))
        yield from sorted(filter(isprime, nind))
print(list(islice(agen(), 40))) # Michael S. Branicky, Jun 26 2022

Extensions

a(38) and beyond from Michael S. Branicky, Jun 26 2022