A186751 a(0) = 3; thereafter, a(n) = a(n-1)^2 - 4.

3, 5, 21, 437, 190965, 36467631221, 1329888126870853950837, 1768602429992068534155014726612412013000565

Offset

0,1

Comments

This is to A001566 as 4 is to 2 (subtrahend). This is the k=4 row of the array A[k,0] = 3, A[k,n] = A[k,n-1]^2 - k; A186750 is the k=3 row; and A001566 is the k=2 row. A003096(n+1) is the k=1 row.

Links

Table of n, a(n) for n=0..7.

Example

a(1) = a(0)^2 - 4 = 3^2 - 4 = 5, which is, like a(0), a prime.

Mathematica

NestList[#^2-4&, 3, 10]  (* Harvey P. Dale, Mar 14 2011 *)

Crossrefs

Cf. A001566, A003096, A186750.

Sequence in context: A084253 A153889 A364576 * A280037 A292557 A147442

Adjacent sequences: A186748 A186749 A186750 * A186752 A186753 A186754

Keyword

nonn,easy

Author

Jonathan Vos Post, Feb 26 2011

Status

approved