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Revision History for A031630 (Underlined text is an addition; strikethrough text is a deletion.)

Showing entries 1-10 | older changes
A031630 Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 42.
(history; published version)
#14 by Harvey P. Dale at Thu Aug 10 13:21:32 EDT 2023
STATUS

editing

approved

#13 by Harvey P. Dale at Thu Aug 10 13:21:29 EDT 2023
MATHEMATICA

cf42Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1, 2}, ContinuedFraction[s][[2]]]; len= Length[ cf]; OddQ[len]&&cf[[Floor[len/2]]]==cf[[Ceiling[len/2]]]==42]; Select[Range[ 450000], cf42Q] (* Harvey P. Dale, Aug 10 2023 *)

STATUS

approved

editing

#12 by N. J. A. Sloane at Wed Aug 18 00:10:32 EDT 2021
NAME

Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 42.

Discussion
Wed Aug 18 00:10 
OEIS Server: https://oeis.org/edit/global/2908
#11 by Hugo Pfoertner at Sun Jul 11 07:48:57 EDT 2021
STATUS

proposed

approved

#10 by Jon E. Schoenfield at Sun Jul 11 07:39:42 EDT 2021
STATUS

editing

proposed

#9 by Jon E. Schoenfield at Sun Jul 11 07:39:40 EDT 2021
NAME

Numbers nk such that the continued fraction for sqrt(nk) has odd period and central terms 42.

STATUS

approved

editing

#8 by Georg Fischer at Sun Jun 16 03:30:47 EDT 2019
STATUS

editing

approved

#7 by Georg Fischer at Sun Jun 16 03:30:44 EDT 2019
DATA

1765, 11261, 21953, 22549, 36181, 36562, 37330, 53945, 54877, 55817, 132058, 165197, 166825, 199357, 235754, 238673, 240629, 242593, 243578, 277301, 283649, 284714, 285781, 287921, 337129, 372941, 377837, 426065, 427370, 428677, 431297

EXTENSIONS

First term 1765 removed by Georg Fischer, Jun 16 2019

STATUS

approved

editing

#6 by Russ Cox at Fri Mar 30 18:35:30 EDT 2012
AUTHOR

_David W. Wilson (davidwwilson(AT)comcast.net)_

Discussion
Fri Mar 30 18:35 
OEIS Server: https://oeis.org/edit/global/202
#5 by N. J. A. Sloane at Sat Jun 12 03:00:00 EDT 2004
NAME

ContinuedNumbers n such that continued fraction for sqrt(n) has odd period and central terms 42.

KEYWORD

nonn,new

nonn

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Last modified August 29 21:13 EDT 2024. Contains 375518 sequences. (Running on oeis4.)