login
A188159
Odd numbers k such that 1^((k-1)/2) + 2^((k-1)/2) + ... + (k-1)^((k-1)/2) <> 0 (mod k).
1
9, 21, 25, 33, 45, 49, 57, 65, 69, 81, 93, 105, 117, 121, 129, 133, 141, 145, 153, 165, 169, 177, 185, 189, 201, 213, 217, 225, 237, 249, 261, 265, 273, 285, 289, 297, 301, 305, 309, 321, 333, 341, 345, 357, 361, 369, 381, 385, 393, 405, 417, 425, 429, 441, 453, 465, 469, 477, 481, 489, 501, 505, 513, 525, 529, 537
OFFSET
1,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
J. M. Grau, Florian Luca, Antonio M. Oller-Marcen, On a variant of Giuga numbers, arXiv:1103.3428 [math.NT], 2011.
MAPLE
isA188159 := proc(n) if type(n, 'odd') then add( i^((n-1)/2), i=1..n-1) ; is(% mod n <>0 ); else false; end if; end proc:
for n from 1 to 350 by 2 do if isA188159(n) then printf("%d, ", n) ; end if; end do: # R. J. Mathar, Mar 30 2011
MATHEMATICA
okQ[n_] := Mod[Sum[PowerMod[j, (n-1)/2, n], {j, n-1}], n]==0; Select[Range[1, 1000, 2], okQ]
PROG
(PARI) is(n)=if(n%2==0, return(0)); my(e=(n-1)/2); sum(k=1, n-1, Mod(k, n)^e)!=0 \\ Charles R Greathouse IV, Feb 04 2013
CROSSREFS
Sequence in context: A210251 A143791 A091113 * A272600 A359161 A327862
KEYWORD
nonn
AUTHOR
STATUS
approved