A143257 - OEIS

%I #33 Feb 12 2024 08:35:23

%S 1,1,1,3,3,15,45,441,441,3213,16059,172569,517671,6695325,43746885,

%T 903732249,903732249,14611840389,110769926061,1248788195355,

%U 12439562858721,154437141889677,1902100636851663,51339101124195573,255363550208935617,4458722921105347251

%N Reverse binary expansion of the factorial numbers.

%F a(n) = A030101(n!).

%p A143257 := proc(n)

%p     A030101(n!) ;

%p end proc:

%p seq(A143257(n),n=0..10) ; # _R. J. Mathar_, Mar 10 2015

%t a[n_] := FromDigits[ Reverse@ IntegerDigits[n!, 2], 2];

%t Array[a, 23] (* _Robert G. Wilson v_, Mar 11 2015 *)

%o (PARI) a(n) = my(v=binary(n!), s); forstep(i=#v, 1, -1, s+=s+v[i]); s \\ _Michel Marcus_, May 18 2013

%Y Cf. A000142, A030101, A098957.

%K nonn,base

%O 0,4

%A _Roger L. Bagula_ and _Gary W. Adamson_, Oct 21 2008

%E Edited and renamed by _Michel Marcus_, May 18 2013