A107291 Numbers n such that 10^n*(10^7*(-1+10^n)+6083806)+10^n-1 is prime.

8, 33, 41, 495, 657, 1904, 4497

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

Table of n, a(n) for n=1..7.

R. Ondrejka, The Top Ten: a Catalogue of Primal Configurations.

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

Adjacent sequences: A107288 A107289 A107290 * A107292 A107293 A107294

Keyword

base,nonn

Author

Jason Earls, May 20 2005

Status

approved