login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A178531 Numbers n such that 10^n - 93 is prime. 0
2, 3, 4, 5, 6, 7, 11, 57, 61, 70, 127, 223, 237, 240, 310, 467, 651, 1935, 2333, 3457, 4456, 6048, 11289, 12150, 24693, 28437, 31123, 32909, 52041, 58225, 68297 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The next term, if it exists, is > 100000.

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "99907".

LINKS

Table of n, a(n) for n=1..31.

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

Index entries for primes involving repunits.

EXAMPLE

10^3 - 93 = 907 which is a prime number.

MATHEMATICA

m=1000; For[n=1, n<m, If[PrimeQ[10^n-93], Print[n]]; n++ ]

PROG

(PARI) is(n)=ispseudoprime(10^n-93) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A108330, A108328.

Sequence in context: A059768 A271835 A118599 * A175500 A222259 A243575

Adjacent sequences:  A178528 A178529 A178530 * A178532 A178533 A178534

KEYWORD

more,nonn

AUTHOR

Robert Price, Dec 23 2010

EXTENSIONS

a(29-31)=52041,58225,68297 from Robert Price, May 29 2011

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified September 26 05:09 EDT 2017. Contains 292502 sequences.