2,2

a(3)=12 because the difference between (3!)^2=36 and the next smaller factorial 4!=24 is 12.

Cf. A121347 [Largest number k such that (n!)^2-k!>0].

Sequence in context: A159534 A126603 A092704 this_sequence A112363 A089956 A003749

Adjacent sequences: A121345 A121346 A121347 this_sequence A121349 A121350 A121351

nonn

Hugo Pfoertner (hugo(AT)pfoertner.org), Aug 15 2006