OFFSET
0,4
COMMENTS
Apparently, also numerator of 2^(n*(n-1)/2)/n!. - N. J. A. Sloane, Dec 31 2010
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..82
FORMULA
a(n) = 2^binomial(n+1,2)/denominator(binomial(2*n,n)/4^n).
a(n) = 2^A127944(n).
MAPLE
a:=n->2^(binomial(n+1, 2))/denom(binomial(2*n, n)/4^n); seq(a(n), n=0..17); # Muniru A Asiru, Dec 10 2018
MATHEMATICA
Table[2^Binomial[n+1, 2]/Denominator[Binomial[2*n, n]/4^n], {n, 0, 25}] (* G. C. Greubel, May 01 2018 *)
PROG
(PARI) for(n=0, 25, print1(2^(binomial(n+1, 2))/denominator(binomial(2*n, n)/4^n), ", ")) \\ G. C. Greubel, May 01 2018
(PARI) a(n) = numerator(2^(n*(n-1)/2)/n!); \\ Altug Alkan, May 02 2018
(Magma) [2^(Binomial(n+1, 2))/Denominator(Binomial(2*n, n)/4^n): n in [0..25]]; // G. C. Greubel, May 01 2018
(Sage) [2^binomial(n+1, 2)/denominator(binomial(2*n, n)/4^n) for n in range(30)] # G. C. Greubel, Dec 09 2018
(GAP) List([0..30], n-> 2^(Binomial(n+1, 2))/DenominatorRat(Binomial(2*n, n)/4^n)); # G. C. Greubel, Dec 09 2018
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Feb 08 2007
STATUS
approved