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 A201397 Decimal expansion of x satisfying x^2+2=sec(x) and 0
 1, 2, 9, 5, 4, 5, 9, 6, 4, 6, 4, 1, 5, 4, 7, 8, 7, 6, 8, 6, 2, 9, 9, 1, 3, 2, 7, 0, 7, 1, 8, 6, 4, 1, 5, 8, 9, 7, 6, 7, 2, 7, 4, 8, 2, 7, 0, 6, 8, 7, 1, 3, 1, 6, 1, 6, 0, 5, 1, 8, 1, 4, 3, 0, 2, 1, 7, 4, 9, 5, 1, 2, 6, 5, 9, 9, 3, 0, 9, 5, 5, 9, 7, 8, 6, 7, 4, 3, 9, 4, 7, 1, 9, 8, 8, 4, 7, 9, 9 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For many choices of a and c, there are exactly two values of x satisfying a*x^2+c=sec(x) and 0 {0, 0}}] r = x /. FindRoot[f[x] == g[x], {x, 1.2, 1.3}, WorkingPrecision -> 110] RealDigits[r]    (* A201397 *) (* Program 2: implicit surface of u*x^2+v=sec(x) *) Remove["Global`*"]; f[{x_, u_, v_}] := u*x^2 + v - Sec[x]; t = Table[{u, v, x /. FindRoot[f[{x, u, v}] == 0, {x, .1, 1}]}, {v, 0, 1}, {u, 2 + v, 10}]; ListPlot3D[Flatten[t, 1]]  (* for A201397 *) CROSSREFS Cf. A201280, A200614. Sequence in context: A021776 A241995 A019708 * A077124 A051491 A253169 Adjacent sequences:  A201394 A201395 A201396 * A201398 A201399 A201400 KEYWORD nonn,cons AUTHOR Clark Kimberling, Dec 01 2011 STATUS approved

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Last modified November 12 12:43 EST 2018. Contains 317109 sequences. (Running on oeis4.)