Let and ℬ be real (or complex) algebras. We investigate the stability of a sequence F = {f₀, f₁, · · ·, f_n, · · ·} of mappings from into ℬ satisfying the higher functional equation: fn(x+y+zw)=fn(x)+fn(y)+∑i+j=ni≤j[fi(z)fj(w)+cijfi(w)fj(z)]

for each n = 0, 1, · · · and all , where cij={1if i≠j,0if i=j.

Keywords: higher functional equation, stability.