N. Kishore, Proc. Amer. Math. Soc. 14 527 (1963), considered the Rayleigh functions σ n (ν) = ∞ k=1 j −2n νk , n = 1, 2,. . ., where the j νk are the (non-zero) zeros of the Bessel function J ν (z) and has provided a convolution type sum formula for finding σ n in terms of σ 1 ,. .. , σ n−1. Here we investigate corresponding expressions for sums of reciprocal powers of zeros τ n of derivatives and other functions related to Bessel functions. It turns out that we can get results similar to Kishore's expressing τ n in terms of τ 1 ,. .. , τ n−1 and σ 1 ,. .. , σ n .