A143257 Reverse binary expansion of the factorial numbers.

1, 1, 1, 3, 3, 15, 45, 441, 441, 3213, 16059, 172569, 517671, 6695325, 43746885, 903732249, 903732249, 14611840389, 110769926061, 1248788195355, 12439562858721, 154437141889677, 1902100636851663, 51339101124195573, 255363550208935617, 4458722921105347251

Offset: 0

Author

Roger L. Bagula and Gary W. Adamson, Oct 21 2008

Keywords

• nonn
• base

Crossrefs

Cf. A000142, A030101, A098957.

Programs

Maple

A143257 := proc(n)
    A030101(n!) ;
end proc:
seq(A143257(n),n=0..10) ; # R. J. Mathar, Mar 10 2015

Mathematica

a[n_] := FromDigits[ Reverse@ IntegerDigits[n!, 2], 2];
Array[a, 23] (* Robert G. Wilson v, Mar 11 2015 *)

PARI

a(n) = my(v=binary(n!), s); forstep(i=#v, 1, -1, s+=s+v[i]); s \\ Michel Marcus, May 18 2013

Formula

a(n) = A030101(n!).

Extensions

Edited and renamed by Michel Marcus, May 18 2013