A173098 a(1)=1, a(2)=2, a(n)=2*a(n-2)*a(n-1)-a(n-1).

1, 2, 2, 6, 18, 198, 6930, 2737350, 37936933650, 207693292716721350, 15758493330480878908260133650, 6545866736124132578837836330405530973356721350

Offset

1,2

Links

Table of n, a(n) for n=1..12.

Mathematica

a=1; b=2; lst={a, b}; Do[c=2*a*b-b; AppendTo[lst, c]; a=b; b=c, {n, 12}]; lst
RecurrenceTable[{a[1]==1, a[2]==2, a[n]==2a[n-2]a[n-1]-a[n-1]}, a, {n, 14}] (* Harvey P. Dale, Jan 27 2012 *)

Crossrefs

Cf. A173093, A173094, A173096, A173097

Sequence in context: A176754 A365103 A357537 * A370836 A233113 A366731

Adjacent sequences: A173095 A173096 A173097 * A173099 A173100 A173101

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Feb 09 2010

Status

approved