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A158462 a(n)=36*n^2-6 (n>0) +0
2
30, 138, 318, 570, 894, 1290, 1758, 2298, 2910, 3594, 4350, 5178, 6078, 7050, 8094, 9210, 10398, 11658, 12990, 14394, 15870, 17418, 19038, 20730, 22494, 24330, 26238, 28218, 30270, 32394, 34590, 36858, 39198, 41610, 44094, 46650, 49278, 51978 (list; graph; listen)
OFFSET

1,1

COMMENT

If A=[A158462] 36*n.^2-6 (n>0, 30, 138, 318,.,); Y=[A005843] 2*n (n>0, 2, 4, 6,.,); X = [A158463] 12*n^2-1 (n>0, 11, 47, 107, .,), we have, for all terms, Pell's equation X^2-A*Y^2=1. Example: 11^2-30*2^2=1; 47^2-138*4^2=1; 107^2-318*6^2=1.

LINKS

Wolfram MathWorld, Pell Equation

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

Edward Everett Withford, Pell Equation

FORMULA

a(n)=36*n^2-6 (n>0)

EXAMPLE

For n=1, a(1)=30; n=2, a(2)=138; n=3, a(3)=318

CROSSREFS

Cf. A005843, A158463

Sequence in context: A100147 A079588 A117750 this_sequence A064495 A124958 A126417

Adjacent sequences: A158459 A158460 A158461 this_sequence A158463 A158464 A158465

KEYWORD

nonn

AUTHOR

Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 19 2009

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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