A178436 Numbers n such that 10^n - 77 is prime.

2, 4, 5, 14, 44, 64, 103, 282, 643, 670, 818, 1092, 1775, 1856, 4080, 4178, 4498, 6815, 8293, 10112, 12023, 13643

Offset

1,1

Comments

The next term, if one exists, is >100000. - Robert Price, Apr 25 2011

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "99923".

Links

Table of n, a(n) for n=1..22.

Makoto Kamada, List of near-repdigit-related prime numbers.

Index entries for primes involving repunits.

Example

10^4 - 77 = 9923 which is a prime number.

Mathematica

nMax=1000; Do[If[PrimeQ[10^n-77], Print[n]], {n, nMax}]

Prog

(PARI) is(n)=ispseudoprime(10^n-77) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A108330, A108328.

Sequence in context: A306919 A373950 A295031 * A370959 A328230 A229131

Adjacent sequences: A178433 A178434 A178435 * A178437 A178438 A178439

Keyword

more,nonn

Author

Robert Price, Dec 21 2010

Status

approved