3617721domain: NAppears in sequencesa(n) is the unique odd positive solution y of 2^n = 7x^2 + y^2.at n=41A077021a(n) is the least odd composite number m such that nextprime(p*m) > p*nextprime(m) where p is the n-th prime.at n=27A117103Expansion of (1-4x^2)/(1+3x+4x^2).at n=21A128415