A350981 Union of A350979 and A350980.

1, 17, 652, 4700, 165985, 1194161, 42159916, 303312572, 10708453057, 77040199505, 2719904916940, 19567907362076, 690845140450081, 4970171429768177, 175471945769404012, 1262403975253755260, 44569183380288169345, 320645639543024068241, 11320397106647425609996, 81442730039952859578332

Offset

1,2

Comments

Arises in studying the equation x^3 - 7*y^2 = 1.

References

P.-F. Teilhet, Query 2228, L'Intermédiaire des Mathématiciens, 11 (1904), 44-45.

Links

Table of n, a(n) for n=1..20.

Index entries for linear recurrences with constant coefficients, signature (1,254,-254,-1,1).

Formula

From Chai Wah Wu, Mar 06 2022: (Start)

a(n) = a(n-1) + 254*a(n-2) - 254*a(n-3) - a(n-4) + a(n-5) for n > 5.

G.f.: x*(4*x^4 + 16*x^3 - 381*x^2 - 16*x - 1)/((x - 1)*(x^2 - 16*x + 1)*(x^2 + 16*x + 1)). (End)

4*a(n) = 7*( -A077412(n)+17*A077412(n-1)) -3*( (-1)^n*A077412(n)+15*(-1)^(n-1)*A077412(n-1)) -6 . - R. J. Mathar, Mar 09 2022

Crossrefs

Cf. A350979, A350980.

Sequence in context: A265678 A200907 A203170 * A063941 A089018 A118769

Adjacent sequences: A350978 A350979 A350980 * A350982 A350983 A350984

Keyword

nonn,easy

Author

N. J. A. Sloane, Mar 06 2022

Status

approved