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!)
A208400 Smallest integer k such that k*n+1 is a prime dividing (n^n)^2 + 1. 1
8, 24, 16384, 8, 216, 1937780208, 24, 720, 167632, 22896, 8, 29256, 72, 2240, 3728099320468576, 8, 612214200, 64, 3800, 176, 40, 18624, 8, 160, 336, 19656, 280, 270006232334172274751152473116790619162839546306934626321438592627063115205009840, 8, 13392, 8568 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Table of n, a(n) for n=2..32.

EXAMPLE

a(3) = 24 because (3^3)^2 + 1 =2*5*73 and the smallest prime divisor of the form k*n+1 is 73 = 24*3+1 => k = 24.

MATHEMATICA

Table[p=First/@FactorInteger[(n^n)^2+1]; (Select[p, Mod[#1, n] == 1 &, 1][[1]]

- 1)/n, {n, 2, 20}]

CROSSREFS

Cf. A208399.

Sequence in context: A166483 A274303 A132586 * A103953 A076444 A023056

Adjacent sequences:  A208397 A208398 A208399 * A208401 A208402 A208403

KEYWORD

nonn

AUTHOR

Michel Lagneau, Feb 27 2012

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 April 15 07:59 EDT 2021. Contains 342975 sequences. (Running on oeis4.)