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

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, 169, 144, 182, 203, 205, 186, 208, 242, 289, 245, 210, 333, 285, 286, 180, 410, 413, 430, 374, 420, 529, 423, 376, 490, 625, 578, 546, 689, 585, 605, 476, 760, 841, 767, 710

Offset: 1

Author

R. J. Mathar, Aug 27 2013

Keywords

• nonn
• easy

Comments

Sum over the odd-numbered columns in row n of A048152.

Crossrefs

Cf. A000447.

Programs

Maple

A228587 := proc(n)
        local a,o ;
        a := 0 ;
        for o from 1 to n-1 by 2 do
                a := a+ modp(o^2,n) ;
        end do:
        a ;
end proc:

Formula

a(n) = sum_{k=1,3,5,...,n-1} (k^2 mod n).

a(n) <= A048153(n).

A187468(n) = a(2^n).