The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A143257 Reverse binary expansion of the factorial numbers. 2
 1, 1, 3, 3, 15, 45, 441, 441, 3213, 16059, 172569, 517671, 6695325, 43746885, 903732249, 903732249, 14611840389, 110769926061, 1248788195355, 12439562858721, 154437141889677, 1902100636851663, 51339101124195573 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS This seems to be a(n) = A003188(A049606(n)). - R. J. Mathar, Nov 11 2011 Sequence has been renamed, old name was "Sequence of sum of Gray code Binary digits for Factorial sequence : a(n)=GrayCodeBinarySum[n!).". LINKS Table of n, a(n) for n=1..23. Weisstein, Eric W., Gray code, MathWorld. FORMULA a(n) = A030101(n!). MAPLE A143257 := proc(n) A030101(n!) ; end proc: seq(A143257(n), n=1..10) ; # R. J. Mathar, Mar 10 2015 MATHEMATICA GrayCodeList[k_] := Module[{b = IntegerDigits[k, 2], i}, Do[ If[b[[i - 1]] == 1, b[[i]] = 1 - b[[i]]], {i, Length[b], 2, -1} ]; b ]; a[n_] = GrayCodeList[n! ]; a0 = Table[Sum[a[n][[m + 1]]*2^m, {m, 0, Length[a[n]] - 1}], {n, 1, 200}] f[n_] := FromDigits[ Reverse@ IntegerDigits[n!, 2], 2]; Array[f, 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 Cf. A098957. Sequence in context: A160624 A049606 A046126 * A089403 A239600 A111674 Adjacent sequences: A143254 A143255 A143256 * A143258 A143259 A143260 KEYWORD nonn AUTHOR Roger L. Bagula and Gary W. Adamson, Oct 21 2008 EXTENSIONS Edited and renamed by Michel Marcus, May 18 2013 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 29 07:13 EDT 2023. Contains 363029 sequences. (Running on oeis4.)