203396domain: NAppears in sequencesDenominators of continued fraction convergents to sqrt(421).at n=13A041801Product_{n>=1} (1 + a(n)*x^n) = 1 + Sum_{n>=1} phi(n)*x^n, where phi = A000010.at n=34A353925Product_{n>=1} 1 / (1 - a(n)*x^n) = 1 + Sum_{n>=1} phi(n)*x^n, where phi = A000010.at n=34A353948