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 A241407 Numbers n such that n^2 == -1 (mod 73). 2
 27, 46, 100, 119, 173, 192, 246, 265, 319, 338, 392, 411, 465, 484, 538, 557, 611, 630, 684, 703, 757, 776, 830, 849, 903, 922, 976, 995, 1049, 1068, 1122, 1141, 1195, 1214, 1268, 1287, 1341, 1360, 1414, 1433, 1487, 1506, 1560, 1579, 1633, 1652, 1706, 1725 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers n such that n == 27 or 46 (mod 73). LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 Index entries for linear recurrences with constant coefficients, signature (1,1,-1). FORMULA G.f.: x*(27 + 19*x + 27*x^2)/((1 + x)*(1 - x)^2). a(n) = a(n-1) + a(n-2) - a(n-3) for n>2. a(n) = a(n-2) + 73 for all n>2. a(n) = -27*(-1)^n + 73*floor(n/2). MATHEMATICA Select[Range[1500], PowerMod[#, 2, 73] == 72 &] (* or *) CoefficientList[ Series[(27 + 19 x + 27 x^2)/((1 + x) (1 - x)^2), {x, 0, 100}], x] Table[73n+{27, 46}, {n, 0, 30}]//Flatten (* or *) LinearRecurrence[{1, 1, -1}, {27, 46, 100}, 60] (* Harvey P. Dale, Jun 13 2017 *) PROG (MAGMA) I:=[27, 46, 100]; [n le 3 select I[n] else Self(n-1)+Self(n-2)-Self(n-3): n in [1..50]] /* or */ [-27*(-1)^n+73*Floor(n/2): n in [1..50]]; CROSSREFS Cf. similar sequences listed in A155107. Sequence in context: A275250 A223019 A059658 * A153260 A254209 A155137 Adjacent sequences:  A241404 A241405 A241406 * A241408 A241409 A241410 KEYWORD nonn,easy AUTHOR Vincenzo Librandi, Apr 25 2014 STATUS approved

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Last modified May 19 03:12 EDT 2019. Contains 323377 sequences. (Running on oeis4.)