37809domain: NAppears in sequencesG.f.: Sum_{n>=0} x^n * Product_{k=1..n} (k - x) / (1 - k*x).at n=7A231172G.f. = b(2)*b(4)*b(6)/(x^8+x^6-x^5-x^3-x+1), where b(k) = (1-x^k)/(1-x).at n=22A266333Numbers k of the form 4m+1 for which A087808(sigma(k)) is equal to 2*A087808(k).at n=2A332445