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A107291
Numbers k such that 10^k*(10^7*(-1+10^k)+6083806) + 10^k - 1 is prime.
0
8, 33, 41, 495, 657, 1904, 4497, 9369, 11096, 11465, 12542, 20819
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)
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
Cf. A079652.
Sequence in context: A131547 A044085 A319524 * A044466 A022274 A118312
KEYWORD
base,nonn,more
AUTHOR
Jason Earls, May 20 2005
EXTENSIONS
a(8)-a(12) from Michael S. Branicky, Sep 21 2024
STATUS
approved