A076516 Primes p such that (p-1) and the period length of 1/p are both squares.
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
Offset: 1
Keywords
Examples
(17-1) = 16 is square and 1/17=0.0588235294117647(0588...) with a decimal period length = 16, square, hence 17 is in the sequence
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..230
Programs
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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 *)