1,2

Using double factorials (!!) augments A064818 for example by 3=3!! and by 15=(5!!)*1=(5!!)/1=(5!!)^1.

Cf. A064818

Sequence in context: A047176 A037175 A048613 this_sequence A030072 A064219 A124164

Adjacent sequences: A162887 A162888 A162889 this_sequence A162891 A162892 A162893

more,nonn

Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), Jul 16 2009

Definition rephrased by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 27 2009