login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A285887 Primes of the form (1 + x)^y + (-x)^y where y is a divisor of x. 4
13, 37, 41, 127, 271, 313, 421, 881, 1013, 1201, 1801, 1861, 2113, 2269, 2381, 2791, 3613, 4651, 5101, 5419, 6211, 7057, 7321, 9941, 10513, 10657, 12097, 13267, 13613, 14281, 16381, 19927, 20201, 21013, 21841, 24421, 24571, 26227, 30013, 33391, 34061, 35317, 41761, 45757, 47741, 49297 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If x = y then: 13, 37, 881, 4651, 1273609, ...

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

J. S. Gerasimov, x^(y + 1) - y^x, SeqFan list, Aug 18 2014.

EXAMPLE

13 is in this sequence because (1 + 2)^2 + (-2)^2 = 13 is prime where 2 is divisor of 2.

MAPLE

N:= 100000: # To get terms <= N

Res:= NULL:

for y from 2 while 2^y -1 <= N do

z:= y/2^padic:-ordp(y, 2);

if z > 1 and (z <> y or not isprime(z)) then next fi;

for x from y by y do

  v:= (1+x)^y + (-x)^y;

  if v > N then break fi;

  if isprime(v) then Res:= Res, v; fi

od od:

sort(convert({Res}, list)); # Robert Israel, Jan 05 2020

MATHEMATICA

Union@ Flatten@ Table[Select[Map[(1 + n)^# + (-n)^# &, Divisors@ n], PrimeQ], {n, 200}] (* Michael De Vlieger, Apr 29 2017 *)

CROSSREFS

Cf. A285886, A285888.

Sequence in context: A220462 A280997 A185006 * A063913 A119705 A155560

Adjacent sequences:  A285884 A285885 A285886 * A285888 A285889 A285890

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Apr 27 2017

EXTENSIONS

Edited by N. J. A. Sloane, Jan 11 2020

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 6 18:38 EDT 2021. Contains 343586 sequences. (Running on oeis4.)