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A158775 a(n) = 1600*n^2+40. 1
1640, 6440, 14440, 25640, 40040, 57640, 78440, 102440, 129640, 160040, 193640, 230440, 270440, 313640, 360040, 409640, 462440, 518440, 577640, 640040, 705640, 774440, 846440, 921640, 1000040, 1081640, 1166440, 1254440, 1345640, 1440040 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

The sequence satisfies the Pell equation (A158776(n))^2- a(n)*(A005843(n))^2=1.

LINKS

Edward Everett Withford, Pell Equation

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

Wolfram MathWorld, Pell Equation

FORMULA

a(n)=3*a(n-1)-3*a(n-2)+a(n-3). G.f.: -40*x*(41+38*x+x^2)/(x-1)^3. [R. J. Mathar, Jul 26 2009]

CROSSREFS

Cf. A005843, A158776

Sequence in context: A052455 A054808 A206234 * A043464 A002434 A146300

Adjacent sequences:  A158772 A158773 A158774 * A158776 A158777 A158778

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 26 2009

EXTENSIONS

Edited by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 26 2009

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Last modified February 17 04:58 EST 2012. Contains 205985 sequences.