A173097 a(1)=1, a(2)=2, a(n)=2*a(n-2)*a(n-1)-a(n-2).

1, 2, 3, 10, 57, 1130, 128763, 291003250, 74940902830737, 43616092563357042787250, 6537258709293941644669222566000575763, 570259361950353096439107826720562074995499493885695588056250

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-a; AppendTo[lst, c]; a=b; b=c, {n, 11}]; lst
RecurrenceTable[{a[1]==1, a[2]==2, a[n]==2a[n-2]a[n-1]-a[n-2]}, a, {n, 15}] (* Harvey P. Dale, Sep 10 2016 *)

Crossrefs

Cf. A173093, A173094, A173096

Sequence in context: A181927 A066526 A093856 * A088221 A206296 A124923

Adjacent sequences: A173094 A173095 A173096 * A173098 A173099 A173100

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Feb 09 2010

Status

approved