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URL: https://oeis.org/A350981

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A350981
Union of A350979 and A350980.
4
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.
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
MATHEMATICA
LinearRecurrence[{1, 254, -254, -1, 1}, {1, 17, 652, 4700, 165985}, 20] (* Paolo Xausa, Feb 06 2026 *)
CROSSREFS
Sequence in context: A265678 A200907 A203170 * A063941 A089018 A118769
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Mar 06 2022
STATUS
approved