OFFSET
-1,2
COMMENTS
Partial products of A087289. - Michel Marcus, Feb 15 2014
LINKS
Vincenzo Librandi, Table of n, a(n) for n = -1..50
J. A. Thas, Old and new results on spreads and ovoids of finite classical polar spaces, Annals of Discrete Mathematics, Vol. 52, 1992, pp. 529-544, Combinatorics '90 — Recent Trends and Applications.
FORMULA
a(n) ~ c * 2^(n*(n+2)), where c = 2*QPochhammer(-1/2, 1/4) = 3.5167992012887276... . - Vaclav Kotesovec, Oct 19 2016
MATHEMATICA
Table[Product[2^(2k+1)+1, {k, 0, n}], {n, -1, 15}] (* Harvey P. Dale, Jun 21 2011 *)
Table[QPochhammer[-2, 4, n + 1], {n, -1, 15}] (* Vladimir Reshetnikov, Oct 18 2016 *)
PROG
(PARI) a(n) = prod(k=0, n, 2^(2*k+1)+1); \\ Michel Marcus, Oct 17 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jul 03 2003
STATUS
approved