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 A127042 Primes p such that denominator of Sum_{k=1..p-1} 1/k^2} is a square. 12
 2, 3, 5, 7, 17, 19, 29, 31, 37, 41, 97, 127, 131, 211, 223, 227, 229, 233, 239, 241, 439, 443, 449, 457, 461, 463, 727, 733, 739, 743, 751, 757, 761, 769, 773, 863, 877, 881, 883, 887, 967, 971, 977, 983, 991, 997, 1009, 1013, 1187, 1193, 1201, 1901, 1907, 1913, 1931, 1933 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS MATHEMATICA a = {}; Do[If[Sqrt[Denominator[Sum[1/x^2, {x, 1, Prime[x] - 1}]]] == Floor[Sqrt[Denominator[Sum[1/x^2, {x, 1, Prime[x] - 1}]]]], AppendTo[a, Prime[x]]], {x, 1, 50}]; a CROSSREFS Cf. A061002, A034602, A127029. Sequence in context: A113029 A090432 A301918 * A069802 A067954 A061248 Adjacent sequences:  A127039 A127040 A127041 * A127043 A127044 A127045 KEYWORD nonn AUTHOR Artur Jasinski, Jan 03 2007 EXTENSIONS More terms from Franklin T. Adams-Watters, Jan 21 2012 STATUS approved

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Last modified January 17 23:37 EST 2020. Contains 330995 sequences. (Running on oeis4.)