A145506 a(n+1)=a(n)^2+2*a(n)-2 and a(1)=6

6, 46, 2206, 4870846, 23725150497406, 562882766124611619513723646, 316837008400094222150776738483768236006420971486980606

Offset

1,1

Comments

General formula for a(n+1)=a(n)^2+2*a(n)-2 and a(1)=k+1 is a(n)=Floor[((k + Sqrt[k^2 + 4])/2)^(2^((n+1) - 1))

Essentially the same as A145502. [From R. J. Mathar, Mar 18 2009]

Links

Table of n, a(n) for n=1..7.

Mathematica

aa = {}; k = 6; Do[AppendTo[aa, k]; k = k^2 + 2 k - 2, {n, 1, 10}]; aa
or
k = 5; Table[Floor[((k + Sqrt[k^2 + 4])/2)^(2^(n - 1))], {n, 2, 7}] (*Artur Jasinski*)

Crossrefs

A145502-A145511

Sequence in context: A327364 A015865 A276271 * A256160 A184725 A232495

Adjacent sequences: A145503 A145504 A145505 * A145507 A145508 A145509

Keyword

nonn

Author

Artur Jasinski, Oct 11 2008

Status

approved