A329471 a(n) = a(n-1)^2 + 3 for n >=2 , where a(0) = 1, a(1) = 3.

1, 3, 12, 147, 21612, 467078547, 218162369067631212, 47594819277201331861096436836588947, 2265266822029455509816214491130485582138030749246532017266850242568812

Offset

0,2

Comments

(a(n)) is a strong divisibility sequence.

Links

Table of n, a(n) for n=0..8.

Formula

a(n) = p(n,0), where p(n,x) is polynomial defined in A329433.

Mathematica

f[x_] := x^2 + 3; u[0, x_] := 1;
u[1, x_] := f[x]; u[n_, x_] := f[u[n - 1, x]]
Table [u[n, x] /. x -> 0, {n, 0, 10}]

Crossrefs

Cf. A329433.

Sequence in context: A322227 A254433 A285603 * A098152 A028301 A356719

Adjacent sequences: A329468 A329469 A329470 * A329472 A329473 A329474

Keyword

nonn

Author

Clark Kimberling, Dec 31 2019

Status

approved