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A156771 729n - 531. 3
198, 927, 1656, 2385, 3114, 3843, 4572, 5301, 6030, 6759, 7488, 8217, 8946, 9675, 10404, 11133, 11862, 12591, 13320, 14049, 14778, 15507, 16236, 16965, 17694, 18423, 19152, 19881, 20610, 21339, 22068, 22797, 23526, 24255, 24984, 25713 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The identity (6561*n^2-9558*n+3482)^2-(81*n^2-118*n+43)*(729*n-531)^2=1 can be written as A156773(n)^2-A156677(n)*a(n)^2=1.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..10000

Index entries for linear recurrences with constant coefficients, signature (2,-1).

FORMULA

a(n) = 2*a(n-1) -a(n-2).

G.f.: x*(198+531*x)/(x-1)^2.

MATHEMATICA

LinearRecurrence[{2, -1}, {198, 927}, 40]

PROG

(MAGMA) I:=[198, 927]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]];

(PARI) a(n)=729*n-531 \\ Charles R Greathouse IV, Dec 23 2011

CROSSREFS

Cf. A156677, A156773.

Sequence in context: A252952 A252945 A158222 * A065697 A159204 A075457

Adjacent sequences:  A156768 A156769 A156770 * A156772 A156773 A156774

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Feb 15 2009

STATUS

approved

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Last modified June 25 22:10 EDT 2019. Contains 324357 sequences. (Running on oeis4.)