45676domain: NAppears in sequencesa(0)=1; a(n) = sigma_2(n) + sigma_3(n).at n=34A092344G.f.: Product_{n=-oo..+oo} (1 + x^n*(1 + x^n)^n).at n=29A293603Pseudoprimes to base 9 that are not squarefree.at n=34A306448a(n) = Sum_{d|n} (n/d)^(n-n/d) * binomial(d+n-2,n-1).at n=8A363667