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

Offset

0,2

Links

Table of n, a(n) for n=0..32.

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] ];

Crossrefs

Cf. A003010.

Sequence in context: A078715 A166874 A046630 * A293353 A293328 A064236

Adjacent sequences: A177871 A177872 A177873 * A177875 A177876 A177877

Keyword

nonn,base

Author

G. L. Honaker, Jr., Dec 13 2010

Extensions

a(21) - a(24) from Klaus Brockhaus, Dec 13 2010

a(25) - a(32) from D. S. McNeil, Dec 13 2010

Status

approved