Abstract
We find formulae for the number of representation of a positive integer n by each of the quadratic forms
x(1)(2) + x(2)(2) + x(3)(2)+ x(4)(2) + 2x(5)(2) + 2x(6)(2) + 6x(7)(2) + 6x(8)(2),
x(1)(2) + x(2)(2) + 2x(3)(2)+ 2x(4)(2) + 2x(5)(2) + 2x(6)(2) + 3x(7)(2) + 3x(8)(2),
x(1)(2) + x(2)(2) + 3x(3)(2)+ 3x(4)(2) + 6x(5)(2) + 6x(6)(2) + 6x(7)(2) + 6x(8)(2),
x(1)(2) + x(2)(2) + x(3)(2)+ x(4)(2) + 2x(5)(2) + 2x(6)(2) + 3x(7)(2) + 3x(8)(2),
x(1)(2) + x(2)(2) + 2x(3)(2)+ 2x(4)(2) + 2x(5)(2) + 2x(6)(2) + 6x(7)(2) + 6x(8)(2),
x(1)(2) + 2x(2)(2) + 2x(3)(2)+ 2x(4)(2) + 2x(5)(2) + 4x(6)(2) + 6x(7)(2) + 6x(8)(2),
2x(1)(2) + 2x(2)(2) + 3x(3)(2)+ 6x(4)(2) + 6x(5)(2) + 6x(6)(2) + 6x(7)(2) + 12x(8)(2),
by using some known convolution sums of divisor functions and known representation formulae for quaternary quadratic forms. Formulae for some other octonary quadratic forms of these type are given before in [4, 5, 6, 11, 17].