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A108847 Palindromic primes in which all internal digits are 8. 8
181, 383, 787, 78887, 9888889, 188888881, 3888888888883, 188888888888881, 3888888888888888888888888888883, 18888888888888888888888888888888888888881 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
a(27) has 1065 digits. - Michael S. Branicky, Jan 27 2023
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..26
PROG
(PARI) n10np1(n, d) = { local(x, y, k); for(x=1, n, for(k=1, 9, y=10^(x+1)*k+floor(10^x*d/9)*10+k; if(isprime(y), print1(y", ")) ) ) }
(Python)
from sympy import isprime
from itertools import count, islice
def agen(): yield from (t for i in count(1) for f in "1379" if isprime(t:=int(f + "8"*i + f)))
print(list(islice(agen(), 10))) # Michael S. Branicky, Jan 27 2023
CROSSREFS
Similar sequences for digit d: A108845 (d=1), A108846 (d=2), A108841 (d=4), A108842 (d=5), A108843 (d=6), A108844 (d=7), A108848 (d=9).
Sequence in context: A142030 A267542 A082444 * A063360 A217499 A113156
KEYWORD
easy,nonn,base
AUTHOR
Cino Hilliard, Jul 11 2005
EXTENSIONS
Name changed by Arkadiusz Wesolowski, Sep 07 2011
One comment moved to A068689 by Michel Marcus, Jan 28 2023
STATUS
approved

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Last modified February 29 10:50 EST 2024. Contains 370425 sequences. (Running on oeis4.)