Numerators of continued fraction convergents to sqrt(421).

Terms

a(0) =20a(1) =21a(2) =41a(3) =554a(4) =2811a(5) =3365a(6) =12906a(7) =16271a(8) =45448a(9) =61719a(10) =107167a(11) =168886a(12) =444939a(13) =4173337a(14) =4618276a(15) =36501269a(16) =114122083a(17) =378867518a(18) =871857119a(19) =2122581756a(20) =7239602387a(21) =23841388917a(22) =174129324806