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A042406
Numerators of continued fraction convergents to sqrt(731).
2
27, 730, 39447, 1065799, 57592593, 1556065810, 84085146333, 2271855016801, 122764256053587, 3316906768463650, 179235729753090687, 4842681610101912199, 261684042675256349433, 7070311833842023346890, 382058523070144517081493
OFFSET
0,1
FORMULA
G.f.: (27 +730*x +27*x^2 -x^3)/(1 -1460*x^2 +x^4). - Vincenzo Librandi, Nov 23 2013
a(n) = 1460*a(n-2) - a(n-4). - Vincenzo Librandi, Nov 23 2013
MATHEMATICA
Numerator[Convergents[Sqrt[731], 30]] (* or *) CoefficientList[Series[(27 + 730 x + 27 x^2 - x^3)/(1 - 1460 x^2 + x^4), {x, 0, 30}], x] (* Vincenzo Librandi, Nov 23 2013 *)
LinearRecurrence[{0, 1460, 0, -1}, {27, 730, 39447, 1065799}, 20] (* Harvey P. Dale, Sep 16 2020 *)
PROG
(Magma) I:=[27, 730, 39447, 1065799]; [n le 4 select I[n] else 1460*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Nov 23 2013
CROSSREFS
Cf. A042407.
Sequence in context: A373218 A307388 A046240 * A279652 A284039 A159668
KEYWORD
nonn,cofr,frac,easy
AUTHOR
STATUS
approved