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 A106176 Numbers n such that 67*n^2 + 67*n + 1 is a square. 1
 0, 16, 1440, 389295, 33994015, 1802660535, 2968421391, 157411709575, 13745486642391, 3714721448623416, 324376465956415720, 17201282202880383816, 28325163305411682840, 1502048325307681783960, 131161685794667995415400, 35446480734732882983897895 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,9542163854,-9542163854,0,0,0,0,-1,1). FORMULA a(1)=0, a(2)=16, a(3)=1440, a(4)=389295, a(5)=33994015, a(6)=1802660535, a(7)=9542163854*a(1)+4771081926-a(6), a(8)=9542163854*a(2)+4771081926-a(5), a(9)=9542163854*a(3)+4771081926-a(4), a(10)=9542163854*a(4)+4771081926-a(3), a(11)=9542163854*a(5)+4771081926-a(2), a(12)=9542163854*a(6)+4771081926-a(1), then a(n)=9542163854*a(n-6)+4771081926-a(n-12). G.f.: -x^2*(16*x^10 +1424*x^9 +387855*x^8 +33604720*x^7 +1768666520*x^6 +1165760856*x^5 +1768666520*x^4 +33604720*x^3 +387855*x^2 +1424*x +16) / ((x -1)*(x^6 -97684*x^3 +1)*(x^6 +97684*x^3 +1)). [Colin Barker, Mar 07 2013] CROSSREFS Cf. A106175 (square roots of 67*a(n)^2+67*a(n)+1). Sequence in context: A221607 A330335 A160251 * A263975 A193128 A223101 Adjacent sequences:  A106173 A106174 A106175 * A106177 A106178 A106179 KEYWORD nonn,easy AUTHOR Pierre CAMI, Apr 24 2005 EXTENSIONS a(15)-a(16) from Colin Barker, Mar 07 2013 STATUS approved

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Last modified April 19 02:19 EDT 2021. Contains 343105 sequences. (Running on oeis4.)