Thanks to everyone who made a donation during our annual appeal! To see the list of donors, or make a donation, see the OEIS Foundation home page.
0,3
Jon E. Schoenfield, Table of n, a(n) for n = 0..30
(3!)! = 6! = 720 has ten binary digits (1011010000), so a(3) = 10.
(PARI) a(n) = length(binary(n!!)) \\ Michel Marcus, Jun 02 2013
Cf. A000197.
Sequence in context: A245903 A100248 A108486 * A003578 A274276 A152600
Adjacent sequences: A152165 A152166 A152167 * A152169 A152170 A152171
base,nonn
Jon E. Schoenfield, Nov 27 2008
approved