The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A072858

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A072858

Primes p such that the period of the decimal expansion of 1/p is a square.
(history; published version)

#24 by Michael De Vlieger at Sat Nov 18 22:24:15 EST 2023

STATUS

proposed

approved

#23 by Jon E. Schoenfield at Sat Nov 18 21:05:14 EST 2023

STATUS

editing

proposed

#22 by Jon E. Schoenfield at Sat Nov 18 21:05:12 EST 2023

NAME

Primes p such that the period of the decimal expansion of 1/p has is a square period length.

EXAMPLE

The period length of 1/17 = 0.05882352941176470588... is 16 = 4^2, hence 17 is in the sequence.

The period length of 1/163 = 81 = 9^2.

STATUS

approved

editing

#21 by Michael De Vlieger at Sat May 21 08:42:34 EDT 2022

STATUS

reviewed

approved

#20 by Michel Marcus at Sat May 21 03:28:23 EDT 2022

STATUS

proposed

reviewed

#19 by Amiram Eldar at Sat May 21 03:13:49 EDT 2022

STATUS

editing

proposed

#18 by Amiram Eldar at Sat May 21 03:07:37 EDT 2022

EXAMPLE

The period length of 1/17 = 0.05882352941176470588... is 16 = 4^2, hence 17 is in the sequence. The period length of 1/163 = 81 = 9^2.

The period length of 1/163 = 81 = 9^2.

#17 by Amiram Eldar at Sat May 21 03:07:16 EDT 2022

NAME

Primes p such that 1/p has a square "period length".

#16 by Amiram Eldar at Sat May 21 03:06:50 EDT 2022

MATHEMATICA

Select[Prime[Range[4000]], IntegerQ @ Sqrt[Length[RealDigits[1/#][[1, 1]]]] &] (* Amiram Eldar, May 21 2022 *)

KEYWORD

easy,nonn,base,changed

#15 by Amiram Eldar at Sat May 21 03:06:07 EDT 2022

LINKS

Amiram Eldar, <a href="/A072858/b072858.txt">Table of n, a(n) for n = 1..10000</a>

STATUS

approved

editing