cp's OEIS Frontend

A228587 Sum of the squares (modulo n) of the odd numbers less than n.

%I A228587 #5 Aug 27 2013 04:34:03
%S A228587 0,1,1,2,5,5,7,4,12,25,22,22,39,49,35,40,68,69,76,50,91,77,92,44,125,
%T A228587 169,144,182,203,205,186,208,242,289,245,210,333,285,286,180,410,413,
%U A228587 430,374,420,529,423,376,490,625,578,546,689,585,605,476,760,841,767,710
%N A228587 Sum of the squares (modulo n) of the odd numbers less than n.
%C A228587 Sum over the odd-numbered columns in row n of A048152.
%F A228587 a(n) = sum_{k=1,3,5,...,n-1} (k^2 mod n).
%F A228587 a(n) <= A048153(n).
%F A228587 A187468(n) = a(2^n).
%p A228587 A228587 := proc(n)
%p A228587         local a,o ;
%p A228587         a := 0 ;
%p A228587         for o from 1 to n-1 by 2 do
%p A228587                 a := a+ modp(o^2,n) ;
%p A228587         end do:
%p A228587         a ;
%p A228587 end proc:
%Y A228587 Cf. A000447.
%K A228587 nonn,easy
%O A228587 1,4
%A A228587 _R. J. Mathar_, Aug 27 2013