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A015906 First k>n such that k | n^k + n. 13
1, 2, 6, 4, 10, 6, 14, 8, 12, 10, 22, 12, 15, 14, 30, 16, 34, 18, 38, 20, 28, 22, 46, 24, 28, 26, 54, 28, 35, 30, 51, 32, 44, 34, 70, 36, 52, 38, 78, 40, 70, 42, 86, 44, 60, 46, 94, 48, 56, 50, 66, 52, 106, 54, 66, 56, 76, 58, 118, 60, 85, 62, 66, 64, 80, 66, 134, 68 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Robert Israel, Table of n, a(n) for n = 0..10000

FORMULA

a(n)=n+1 if n is odd. a(n) <= 2n+2. - Robert Israel, Sep 13 2018

MAPLE

f:= proc(n) local k;

  for k from n+1 do

    if n &^k + n mod k = 0 then return k fi

  od

end proc:

map(f, [$0..100]); # Robert Israel, Sep 13 2018

MATHEMATICA

fk[n_]:=Module[{k=n+1}, While[!Divisible[n^k+n, k], k++]; k]; Array[fk, 70, 0] (* Harvey P. Dale, Jan 28 2019 *)

CROSSREFS

Sequence in context: A333775 A334205 A227389 * A066043 A238642 A145019

Adjacent sequences:  A015903 A015904 A015905 * A015907 A015908 A015909

KEYWORD

nonn,look

AUTHOR

Robert G. Wilson v

EXTENSIONS

a(0)=1 and a(1)=2 inserted by Robert Israel, Sep 13 2018

STATUS

approved

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Last modified May 17 08:41 EDT 2021. Contains 343966 sequences. (Running on oeis4.)