OFFSET
1,1
COMMENTS
These are palprimes with curved digits, i.e., palindromic primes composed of only 0's, 3s, 6s, 8s, or 9s and they have all been proved prime. No more terms up to 7000. Primality proof for the largest: PFGW Version 20041001.Win_Stable (v1.2 RC1b) [FFT v23.8] Primality testing 10^4497*(10^7*(-1+10^4497)+6083806)+10^4497-1 [N+1, Brillhart-Lehmer-Selfridge] Running N+1 test using discriminant 3, base 1+sqrt(3) Running N+1 test using discriminant 3, base 3+sqrt(3) Running N+1 test using discriminant 3, base 5+sqrt(3) 10^4497*(10^7*(-1+10^4497)+6083806)+10^4497-1 is prime! (147.0046s+0.0074s)
LINKS
EXAMPLE
8 is a term because 10^8*(10^7*(-1+10^8)+6083806)+10^8-1 = 99999999608380699999999 is prime.
PROG
(PARI) is(n)=ispseudoprime(10^n*(10^7*(-1+10^n)+6083806)+10^n-1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
base,nonn,more
AUTHOR
Jason Earls, May 20 2005
EXTENSIONS
a(8)-a(12) from Michael S. Branicky, Sep 21 2024
STATUS
approved