A227077 y solutions to the Diophantine equation 2*x^2*(x^2 - 1) = 3*(y^2 - 1)

1, 3, 7, 29, 6761

Offset

0,2

Comments

Also solutions to (2*x^2 - 1)^2 = 6*y^2 - 5 as outlined in A180445, which gives the x solutions to this equation {1, 2, 3, 6, 91}.

(sqrt(2)*sqrt(sqrt(6*a(n)^2 - 5) + 1) - 1)^2 = A038198(n)^2 gives the Ramanujan-Nagell squares listed in A227078.

Links

Table of n, a(n) for n=0..4.

Richard K. Guy, The Strong Law of Small Numbers (example #29).

Mathematica

Select[Table[Sqrt[3-2x^2+2x^4]/Sqrt[3], {x, 0, 100}], IntegerQ]//Union (* Harvey P. Dale, Aug 11 2019 *)

Crossrefs

Cf. A180445, A038198, A227078.

Sequence in context: A113834 A057181 A333393 * A136934 A369083 A201794

Adjacent sequences: A227074 A227075 A227076 * A227078 A227079 A227080

Keyword

nonn

Author

Raphie Frank, Jun 30 2013

Status

approved