Search: id:A048631 Results 1-1 of 1 results found. %I A048631 %S A048631 1,1,2,6,24,120,272,1904,15232,124800,848640,7507200,39738368, %T A048631 433441792,2589116416,30419859456,486717751296,8128101580800, %U A048631 132557598294016,1971862458400768,30421253686034432,512675443057623040 %N A048631 Xfactorials - like factorials but use carryless GF(2)[ X ] polynomial multiplication. %C A048631 In formula X stands for the multiplication in a ring of GF(2)[ X ] polynomials %F A048631 a(0) = 1, a(n) = n X a(n-1) (See the Maple function Xfactorial given below). %p A048631 Xfactorial := proc(n); if(0 = n) then RETURN(1); else RETURN(Xmult(n, Xfactorial(n-1))); fi; end; %p A048631 Xmult := proc(n,m) option remember; if(0 = n) then RETURN(0); else RETURN(XORnos(((n mod 2)*m),Xmult(floor(n/2),m*2))); fi; end; %Y A048631 Cf. A000142, A048720, A048632, A061922. %Y A048631 Sequence in context: A066616 A083267 A130480 this_sequence A062348 A072856 A070946 %Y A048631 Adjacent sequences: A048628 A048629 A048630 this_sequence A048632 A048633 A048634 %K A048631 easy,nonn %O A048631 0,3 %A A048631 Antti Karttunen Search completed in 0.001 seconds