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A157998 a(n)=169*n^2-n (n>0) +0
3
168, 674, 1518, 2700, 4220, 6078, 8274, 10808, 13680, 16890, 20438, 24324, 28548, 33110, 38010, 43248, 48824, 54738, 60990, 67580, 74508, 81774, 89378, 97320, 105600, 114218, 123174, 132468, 142100, 152070, 162378, 173024, 184008, 195330 (list; graph; listen)
OFFSET

1,1

COMMENT

If A=[A157998] 169*n.^2-n (168, 674, 1518,. ,.,); Y=[A010865] 26 (26, 26, 26,..,); X=[A157999] 338*n-1 (337, 675, 1013, ,. .,), we have, for all terms, Pell's equation X^2-A*Y^2=1. Example: 337^2-168 *26^2=1; 675^2-674*26^2=1; 1013^2-1518*26^2=1.

LINKS

Edward Everett Withford, Pell Equation

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

Wolfram MathWorld, Pell Equation

FORMULA

a(n)=169*n^2-n (n>0)

EXAMPLE

For n=1, a(1)=168; n=2, a(2)=674; n=3, a(3)=1518

CROSSREFS

Cf. A010865, A157999

Sequence in context: A158219 A027679 A137863 this_sequence A110285 A070835 A112551

Adjacent sequences: A157995 A157996 A157997 this_sequence A157999 A158000 A158001

KEYWORD

nonn

AUTHOR

Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 11 2009

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Last modified November 29 12:46 EST 2009. Contains 167659 sequences.


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