A178406 Numbers n such that 10^n - 41 is prime.

2, 6, 8, 12, 14, 47, 88, 130, 414, 1388, 1932, 4106, 4412, 12870, 22956, 23932, 27312, 35316, 37169, 43873, 150029

Offset

1,1

Comments

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

a(22) > 2.5*10^5. - Robert Price, Apr 12 2015

Links

Table of n, a(n) for n=1..21.

Makoto Kamada, Near-repdigit numbers of the form AA...AABA.

Makoto Kamada, Prime numbers of the form 99...9959.

Index entries for primes involving repunits.

Example

10^6 - 41 = 999959 which is a prime number.

Mathematica

m=1000; For[n=1, n<m, If[PrimeQ[10^n-41], Print[n]]; n++ ]

Prog

(PARI) is(n)=ispseudoprime(10^n-41) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A108330, A108328.

Sequence in context: A276154 A328770 A138626 * A189515 A190344 A287000

Adjacent sequences: A178403 A178404 A178405 * A178407 A178408 A178409

Keyword

more,nonn

Author

Robert Price, Dec 21 2010

Extensions

a(20)=43873 from Robert Price, Apr 25 2011

a(21) from Kamada data by Robert Price, Apr 12 2015

Status

approved