OFFSET
1,3
LINKS
J. de Gier, Loops, matchings and alternating-sign matrices, arXiv:math.CO/0211285, 2002.
EXAMPLE
3, 5, 87/13, 156/19, 913/95, 1693/155, 69769/5735, 658529/49321, 5002953/345247, 173619/11137, 1616141/97051, 3107877/175741, 239756907/12829093, ...
MAPLE
f3:=proc(n) local j;
(mul(((2*j+1)*(3*j+4))/((j+1)*(6*j+1)), j=0..n-1)-1); end;
t3:=[seq(f3(n), n=1..50)];
map(numer, t3);
map(denom, t3);
MATHEMATICA
Table[Product[(2*j+1)*(3*j+4)/((j+1)*(6*j+1)), {j, 0, n-1}]-1, {n, 1, 20}]//Denominator (* Vaclav Kotesovec, Oct 13 2017 *)
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
N. J. A. Sloane, May 04 2016
STATUS
approved