Polynomials s_k(x;λ) which form a Sheffer sequence with g(t) | = | 1 + e^(λ t) f(t) | = | e^t - 1 and have generating function sum_(k = 0)^∞ (s_k(x;λ))/(k!) t^k = (1 + t)^x/(1 + (1 + t)^λ).