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A076516 Primes p such that (p-1) and the period length of 1/p are both squares. 1
5, 17, 101, 257, 577, 1297, 3137, 5477, 7057, 12101, 13457, 14401, 15377, 24337, 25601, 30977, 33857, 41617, 42437, 44101, 50177, 52901, 55697, 57601, 62501, 65537, 69697, 72901, 80657, 98597, 106277, 122501, 147457, 164837, 184901 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..230

EXAMPLE

(17-1) = 16 is square and 1/17=0.0588235294117647(0588...) with a decimal period length = 16, square, hence 17 is in the sequence

MATHEMATICA

bsQ[n_]:=IntegerQ[Sqrt[n-1]]&&IntegerQ[Sqrt[Length[Flatten[ RealDigits[ 1/n][[1]]]]]]; Select[Prime[Range[2, 17000]], bsQ] (* Harvey P. Dale, May 30 2013 *)

CROSSREFS

Cf. A002496, A072858.

Sequence in context: A254759 A139390 A145824 * A145986 A200992 A034821

Adjacent sequences:  A076513 A076514 A076515 * A076517 A076518 A076519

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Nov 09 2002

STATUS

approved

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Last modified May 26 04:46 EDT 2019. Contains 323579 sequences. (Running on oeis4.)