OFFSET
0,1
COMMENTS
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..22 (shortened by N. J. A. Sloane, Jan 13 2019)
MATHEMATICA
RecurrenceTable[{a[0]==a[1]==a[2]==2, a[n]==a[n-1]a[n-3]-1}, a, {n, 20}] (* Harvey P. Dale, Sep 02 2016 *)
PROG
(Magma) I:=[2, 2, 2]; [n le 3 select I[n] else Self(n-1)*Self(n-3)-1: n in [1..20]]; // Vincenzo Librandi, Nov 14 2011
(PARI) a(n) = if(n<3, 2, a(n-1)*a(n-3) - 1);
vector(20, n, n--; a(n)) \\ G. C. Greubel, Jun 07 2019
(Sage)
def a(n):
if (n==0 or n==1 or n==2): return 2
else: return a(n-1)*a(n-3) -1
[a(n) for n in (0..20)] # G. C. Greubel, Jun 07 2019
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Aug 22 2006
EXTENSIONS
Corrected and extended by Vincenzo Librandi, Nov 14 2011
STATUS
approved