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A156866 729000n - 116820. 3
612180, 1341180, 2070180, 2799180, 3528180, 4257180, 4986180, 5715180, 6444180, 7173180, 7902180, 8631180, 9360180, 10089180, 10818180, 11547180, 12276180, 13005180, 13734180, 14463180, 15192180, 15921180, 16650180, 17379180 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The identity (32805000*n^2-10513800*n+842401)^2-(2025*n^2-3401*n+1428)*(729000*n-116820)^2=1 can be written as A157079(n)^2-A156854(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. 180*x*(3401+649*x)/(x-1)^2.

MATHEMATICA

LinearRecurrence[{2, -1}, {612180, 1341180}, 40]

PROG

(MAGMA) I:=[612180, 1341180]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..40]];

(PARI) a(n)=729000*n-116820 \\ Charles R Greathouse IV, Dec 23 2011

CROSSREFS

Cf. A156854, A156865, A157079.

Sequence in context: A233938 A237784 A230009 * A317480 A206510 A172635

Adjacent sequences:  A156863 A156864 A156865 * A156867 A156868 A156869

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Feb 17 2009

STATUS

approved

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Last modified April 25 23:48 EDT 2019. Contains 322465 sequences. (Running on oeis4.)