42422452969domain: NAppears in sequencesPositive integers m such that m^4 = a^2 + b^2 and a + b = c^2 for some coprime integers a, b, c.at n=4A166929Generalized Somos-5 sequence with a(n) = (-a(n-1)*a(n-4) + 42*a(n-2)*a(n-3))/a(n-5), a(-n) = a(n), a(0) = a(1) = 1, a(2) = 3.at n=9A360187