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Search: id:A158644
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A158644 a(n)=52*n^2+1. +0
2
1, 53, 209, 469, 833, 1301, 1873, 2549, 3329, 4213, 5201, 6293, 7489, 8789, 10193, 11701, 13313, 15029, 16849, 18773, 20801, 22933, 25169, 27509, 29953, 32501, 35153, 37909, 40769, 43733, 46801, 49973, 53249, 56629, 60113, 63701, 67393 (list; graph; listen)
OFFSET

0,2

COMMENT

The identity (52*n^2+1)^2 - (676*n^2+26) * (2*n)^2 = 1 can be written as

the Pell equation (a(n))^2 - A158643(n) * (A005843(n))^2 =1.

LINKS

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

Edward Everett Withford, Pell Equation

Wolfram MathWorld, Pell Equation

FORMULA

a(n)= 3*a(n-1) -3*a(n-2) +a(n-3). G.f.: -(1+50*x+53*x^2)/(x-1)^3.

CROSSREFS

Cf. A005843, A158643

Sequence in context: A008993 A142088 A005146 this_sequence A158656 A142000 A053652

Adjacent sequences: A158641 A158642 A158643 this_sequence A158645 A158646 A158647

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 23 2009

EXTENSIONS

Comment rephrased and redundant formula replaced by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 19 2009

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Last modified December 19 12:50 EST 2009. Contains 171053 sequences.


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