Published online by Cambridge University Press: 20 November 2018
The projectivity of the Whitehead square wn = [in, in] in π2n-1(SN) has been studied by Randall [6] who proved that if wn is projective then n must be a power of 2 or one less than a power of 2. Here we solve the question in the even case, proving by means of bo homology:
Theorem. if and only if n = 1, 2, 4.