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A145020 a(n) = ((7 + sqrt(7))^n - (7 - sqrt(7))^n)^2/28. 0
1, 196, 23716, 2458624, 239754256, 22776846400, 2139058352704, 199857257119744, 18630079167234304, 1734834007938712576, 161472109634377851904, 15026063825688651366400 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..12.

Index entries for linear recurrences with constant coefficients, signature (154,-6468,74088).

FORMULA

From R. J. Mathar, Sep 30 2008: (Start)

G.f.: x(1+42x)/((1-42x)(1-112x+1764x^2)).

a(n) = 154*a(n-1) - 6468*a(n-2) + 74088*a(n-3). (End)

PROG

(MAGMA) Z<x>:=PolynomialRing(Integers()); N<r7>:=NumberField(x^2-7); [ Integers()!a: a in [ ((7+r7)^n-(7-r7)^n)^2/28: n in [1..12] ] ]; // Klaus Brockhaus, Oct 20 2008

CROSSREFS

Sequence in context: A035834 A114761 A076002 * A333641 A260863 A013755

Adjacent sequences:  A145017 A145018 A145019 * A145021 A145022 A145023

KEYWORD

nonn,easy

AUTHOR

Al Hakanson (hawkuu(AT)gmail.com), Sep 29 2008

EXTENSIONS

Extended by R. J. Mathar, Sep 30 2008

STATUS

approved

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Last modified May 16 23:46 EDT 2021. Contains 343957 sequences. (Running on oeis4.)