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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A255730 Numbers n such that n^n - (n-1)^n + n is prime. 0
1, 2, 4, 16, 52, 80 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(6) corresponds to a prime having 153 digits.

If it exists, a(7) > 5000.

n does not have the form 20k+2 (which leads to a multiple of 5) or 42k+26 (which leads to a multiple of 7).

LINKS

Table of n, a(n) for n=1..6.

EXAMPLE

4 is in the sequence because 4^4 - 3^4 + 4 = 179 is prime.

MATHEMATICA

Select[Range[1000], PrimeQ[#^# - (# - 1)^# + #] &]

PROG

(MAGMA) [n: n in [0..500] |IsPrime(n^n - (n-1)^n + n)];

(PARI) is(n)=ispseudoprime(n^n-(n-1)^n+n) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A085682.

Sequence in context: A104354 A153948 A284730 * A010362 A262164 A322940

Adjacent sequences:  A255727 A255728 A255729 * A255731 A255732 A255733

KEYWORD

nonn,more

AUTHOR

Vincenzo Librandi, Mar 13 2015

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 August 24 03:51 EDT 2019. Contains 326260 sequences. (Running on oeis4.)