The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A081231 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A081231

Let p = n-th prime of the form 4k+3, take smallest solution (x,y) to the Pellian equation x^2 - p*y^2 = 1 with x and y >= 1; sequence gives value of x.
(history; published version)

#15 by Joerg Arndt at Sat Feb 25 03:08:39 EST 2023

STATUS

reviewed

approved

#14 by Michel Marcus at Sat Feb 25 02:13:14 EST 2023

STATUS

proposed

reviewed

#13 by Joerg Arndt at Sat Feb 25 02:04:24 EST 2023

STATUS

editing

proposed

#12 by Claude Morin at Fri Feb 24 15:38:05 EST 2023

CROSSREFS

Values of y are in A081231A082394. Equals A002350(p). Cf. A082393.

STATUS

approved

editing

#11 by Jon E. Schoenfield at Sat Mar 28 18:12:08 EDT 2015

STATUS

editing

approved

#10 by Jon E. Schoenfield at Sat Mar 28 18:12:06 EDT 2015

MATHEMATICA

PellSolve[(m_Integer)?Positive] := Module[{cf, n, s}, cf = ContinuedFraction[ Sqrt[m]]; n = Length[ Last[cf]]; If[ OddQ[n], n = 2*n]; s = FromContinuedFraction[ ContinuedFraction[ Sqrt[m], n]]; {Numerator[s], Denominator[s]}]; Transpose[ PellSolve /@ Select[ Prime[ Range[72]], Mod[ #, 4] == 3 &]][[1]] (from * _Robert G. Wilson v _, Sep 02 2004 *)

AUTHOR

N. J. A. Sloane, Apr 18, 2003

STATUS

approved

editing

#9 by Joerg Arndt at Sat Jul 14 10:21:25 EDT 2012

STATUS

proposed

approved

#8 by Vincenzo Librandi at Sat Jul 14 09:05:13 EDT 2012

STATUS

editing

proposed

#7 by Vincenzo Librandi at Sat Jul 14 09:05:00 EDT 2012

LINKS

Vincenzo Librandi, <a href="/A081231/b081231.txt">Table of n, a(n) for n = 1..1000</a>

STATUS

approved

editing

#6 by Russ Cox at Fri Mar 30 17:30:54 EDT 2012

EXTENSIONS

More terms from _Robert G. Wilson v (rgwv(AT)rgwv.com), _, Sep 02 2004

Discussion

Fri Mar 30

17:30

OEIS Server: https://oeis.org/edit/global/156