%I #21 Sep 11 2019 05:03:25

%S 1,8,7,5,1,0,4,0,6,8,7,1,1,9,6,1,1,6,6,4,4,5,3,0,8,2,4,1,0,7,8,2,1,4,

%T 1,6,2,5,7,0,1,1,1,7,3,3,5,3,1,0,6,9,9,8,8,2,4,5,4,1,3,7,1,3,1,0,5,6,

%U 7,9,9,5,2,8,4,0,4,2,8,6,3,8,5,2,6,5,6,6,5,5,0,5,8,1,8,8,6,0,3,7,0,8,4,1,0

%N Decimal expansion of first solution of equation cos(x)*cosh(x) = -1.

%C This is an equation related to a cantilever beam: cos(x)*cosh(x) = -1. The first three solutions are: 1.875 (this sequence), 4.69409 (A076418) and 7.854757 (A076419).

%H Z. Guede, I. Elishakov, <a href="http://dx.doi.org/10.1016/S0960-0779(00)00014-X">A fifth-order polynomial that serves as both buckling and vibration mode of an inhomogeneous structure</a>, Chaos, Solitons and Fractals 12 (7) (2001) 1267-1298.

%e 1.87510406871196116644530824107821416257011173353...

%t RealDigits[x/.FindRoot[Cos[x]Cosh[x]==-1,{x,1.8}, WorkingPrecision->120], 10,120][[1]] (* _Harvey P. Dale_, Jul 24 2011 *)

%o (PARI) solve(x=1, 2, cos(x)*cosh(x) + 1) \\ _Michel Marcus_, Sep 11 2019

%Y Cf. A009398, A076418, A076419.

%Y Cf. A005981, A058258, A008775.

%K easy,nonn,cons

%O 1,2

%A _Zak Seidov_, Oct 10 2002