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A375895
a(n) = (32)^n*sin (nC - nA)/(6 sqrt(15)), where A, B, C are, respectively, the angles opposite sides BC, CA, AB in a triangle ABC having sidelengths |BC| = 2, |CA| = 3, |AB| = 4; ABC is the smallest integer-sided scalene triangle.
1
0, 1, 44, 912, -4928, -1150720, -45585408, -827420672, 10272948224, 1299288489984, 46649194577920, 722093147684864, -15996676749656064, -1443277160214167552, -47123598057775562752, -595522502482817187840, 22051574301918219993088, 1580084311826806480044032
OFFSET
0,3
COMMENTS
If a prime p divides a term, then the indices n such that p divides a(n) comprise an arithmetic sequence; see the Renault paper in References. For a guide to related sequences, see A375880.
FORMULA
a(n) = (32)^n*cos (nC - nA)/(6 sqrt(15)), where A, B, C are, respectively, the angles opposite sides BC, CA, AB in a triangle ABC having sidelengths |BC| = 2, |CA| = 3, |AB| = 4.
a(n) = 122 a(n-1) - 4096 a(n-2), where a(0) = 0, a(1) = 1.
From Stefano Spezia, Sep 23 2024: (Start)
G.f.: x/(1 - 44*x+ 1024*x^2).
E.g.f.: exp(22*x)*sin(6*sqrt(15)*x)/(6*sqrt(15)). (End)
MATHEMATICA
(* Program 1 *)
A[a_, b_, c_] := ArcSin[Sqrt[1 - ((b^2 + c^2 - a^2)/(2 b c))^2]];
{a, b, c} = {2, 3, 4};
Table[TrigExpand[(32)^n Sin[n (A[c, a, b] - A[a, b, c])]/(6 Sqrt[15])], {n, 0, 22}]
(* Program 2 *)
LinearRecurrence[{44, -1024}, {0, 1}, 30]
CROSSREFS
Cf. A375880.
Sequence in context: A183750 A133349 A010838 * A191374 A299466 A010960
KEYWORD
sign,easy
AUTHOR
Clark Kimberling, Sep 22 2024
STATUS
approved