A347864 Left- or right-truncatable primes, restricted to one consecutive zero.

2, 3, 5, 7, 13, 17, 23, 29, 31, 37, 43, 47, 53, 59, 67, 71, 73, 79, 83, 97, 103, 107, 113, 131, 137, 139, 167, 173, 179, 197, 223, 229, 233, 239, 271, 283, 293, 307, 311, 313, 317, 331, 337, 347, 353, 359, 367, 373, 379, 383, 397, 431, 433, 439, 443, 467, 479, 503

Offset

1,1

Comments

There are 16484138 primes in this list, in total. The largest one has 60 digits and there is only one of that length.

Links

Table of n, a(n) for n=1..58.

Prog

(Python)
from sympy import isprime
route = set({})
nums = [i*(10**j) for i in range(1, 10) for j in range(2)]
def addnum(a):
    global route
    for j in nums:
        b = int("{}{}".format(a, j))
        if isprime(b):
            if b not in route:
                route.add(b)
                addnum(b)
    for j in nums:
        b = int("{}{}".format(j, a))
        if isprime(b):
            if b not in route:
                route.add(b)
                addnum(b)
def run():
    for i in nums:
        if isprime(i):
            addnum(i)

Crossrefs

Left- or right-truncatable primes, excluding all 0s: A137812.

The number of primes of length n following these rules: A346662.

Sequence in context: A179336 A080608 A305352 * A137812 A216578 A094317

Adjacent sequences: A347861 A347862 A347863 * A347865 A347866 A347867

Keyword

nonn,fini

Author

Timothy Smith, Jan 25 2022

Status

approved