A196730 - OEIS

%I #6 Mar 30 2012 18:35:59

%S 1,2,4,8,9,10,16,26,32,34,58,64,74,81,82,84,106,122,128,146,178,194,

%T 196,202,218,226,250,256,274,298,314,346,361,362,386,394,441,458,466,

%U 480,482,512,514,538,554,562,586,626,634,674,676,698,706,722,729,746

%N Numbers m such that the sum of the distinct residues of x^m (mod m) is a perfect square, x=0..m-1.

%C m such that A195812(m) is a perfect square.

%e a(8) = 26 because x^26 == > 0, 1, 3, 4, 9, 10, 12, 13, 14, 16, 17, 22, 23, 25  (mod 26), and the sum  = 169 = 13^2.

%p sumSquares := proc(n)

%p local re, x, r ;

%p re := {} ;

%p for x from 0 to n-1 do

%p re := re union { modp(x^n, n) } ;

%p end do:

%p add(r, r=re) ;

%p end proc:

%p for n from 1 to 750 do

%p z:= sqrt(sumSquares(n));

%p if z=floor(z) then

%p printf("%d, ", n);

%p end if;

%p end do: #

%Y Cf. A195812, A196547, A196546, A195637.

%K nonn

%O 1,2

%A _Michel Lagneau_, Oct 05 2011