A097419 a(1) = 2, a(n) = 2*a(n-1)^2 - a(n-1) for n > 1.

2, 6, 66, 8646, 149497986, 44699295486614406, 3996054033999333969062944766851266, 31936895685284700329548847429175178142518023225832967407199564754246

Offset

1,1

Comments

These numbers when factored are 2*3, 2*3*11, 2*3*11*131, 2*3*11*131*17291, 2*3*11*131*17291*298995971, 2*3*11*131*8779*10079*17291*298995971*1010341471, 2*3*11*29*59*131*241*8779*10079*17291*298995971*1010341471*2511683491*7716660340023314591, so a(n) is a prime multiple of a(n-1) for 2<=n<=6. 2,3,11,131,17291,298995971 are A090475 [Beginning with 2, a(n+1) is the least prime == -1 (mod (product a(i), i=1 to n)).]

Links

Table of n, a(n) for n=1..8.

Crossrefs

Cf. A090475.

Sequence in context: A335934 A167006 A087331 * A219037 A156458 A244494

Adjacent sequences: A097416 A097417 A097418 * A097420 A097421 A097422

Keyword

nonn

Author

Gerald McGarvey, Aug 19 2004

Status

approved