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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A171612 Integers n such that (25*10^n)+1 is prime. 0
1, 8, 255, 320, 609, 688, 1436, 3271, 3921, 6520, 19604 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

No others less than 20000.

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "25001".

LINKS

Table of n, a(n) for n=1..11.

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

Index entries for primes involving repunits.

EXAMPLE

For n=8 we have (25*10^8)+1 = 25*100000000+1 = 2500000000+1 = 2500000001, which is prime.

CROSSREFS

Cf. A056797, A056804, A056805, A056806, A056807

Sequence in context: A213412 A226428 A277421 * A053717 A267250 A034674

Adjacent sequences:  A171609 A171610 A171611 * A171613 A171614 A171615

KEYWORD

more,nonn

AUTHOR

Julien Peter Benney (jpbenney(AT)ftml.net), Dec 13 2009

EXTENSIONS

Edited by Ray Chandler, Dec 23 2010

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 26 13:05 EDT 2019. Contains 323586 sequences. (Running on oeis4.)