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A158743 a(n)=37*(37*n^2-1). 1
1332, 5439, 12284, 21867, 34188, 49247, 67044, 87579, 110852, 136863, 165612, 197099, 231324, 268287, 307988, 350427, 395604, 443519, 494172, 547563, 603692, 662559, 724164, 788507, 855588, 925407, 997964, 1073259, 1151292, 1232063 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

The identity (74*n^2-1)^2 - (1369*n^2-37) * (2*n)^2 = 1 can be written as

the Pell equation (A158744(n))^2 - a(n) * (A005843(n))^2 = 1.

LINKS

Wolfram MathWorld, Pell Equation

Edward Everett Withford, Pell Equation

Vincenzo Librandi, X^2-AY^2=1

FORMULA

a(n)= 3*a(n-1) -3*a(n-2) +a(n-3). G.f.: 37*x*(-36-39*x+x^2)/(x-1)^3.

CROSSREFS

Cf. A005843, A158744

Sequence in context: A052072 A050646 A044882 * A188308 A185494 A035862

Adjacent sequences:  A158740 A158741 A158742 * A158744 A158745 A158746

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 25 2009

EXTENSIONS

Comment rewritten and formula replaced by R. J. Mathar, (mathar(AT)strw.leidenuniv.nl), Oct 22 2009

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Last modified February 14 20:38 EST 2012. Contains 205663 sequences.