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URL: https://oeis.org/A143257

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A143257
Reverse binary expansion of the factorial numbers.
2
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
0,4
FORMULA
a(n) = A030101(n!).
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 *)
PROG
(PARI) a(n) = my(v=binary(n!), s); forstep(i=#v, 1, -1, s+=s+v[i]); s \\ Michel Marcus, May 18 2013
CROSSREFS
KEYWORD
nonn,base
AUTHOR
EXTENSIONS
Edited and renamed by Michel Marcus, May 18 2013
STATUS
approved