A177874 - OEIS

A177874

The number of decimal digits in the Lucas-Lehmer number A003010(n).

1, 2, 3, 5, 10, 19, 37, 74, 147, 293, 586, 1172, 2343, 4686, 9371, 18742, 37484, 74967, 149933, 299866, 599731, 1199461, 2398922, 4797844, 9595688, 19191376, 38382751, 76765501, 153531001, 307062002, 614124003, 1228248006, 2456496012, 4912992024, 9825984047

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..34.

FORMULA

a(n) = A055642(A003010(n)).

MATHEMATICA

a=Sqrt[6]; Table[a=a^2-2; Length[IntegerDigits[a]], {n, 0, 20}]

IntegerLength/@NestList[#^2-2&, 4, 33] (* Harvey P. Dale, Jan 19 2018 *)

PROG

(Magma) T:=[ n eq 1 select 4 else Self(n-1)^2-2: n in [1..24] ]; [ #Intseq(T[n]): n in [1..#T] ];