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%I #16 Jul 27 2017 19:27:16
%S 1,2,1,4,5,2,1,8,9,10,11,4,5,2,1,16,17,18,19,20,21,22,23,8,9,10,11,4,
%T 5,2,1,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,16,17,18,19,20,
%U 21,22,23,8,9,10,11,4,5,2,1,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78
%N Take n written in binary. Replace the leftmost run of 1's with just a single 1. a(n) is the decimal equivalent of the result.
%H G. C. Greubel, <a href="/A163509/b163509.txt">Table of n, a(n) for n = 1..1000</a>
%e 29 in binary is 11101. Replace the three 1's on the left of the binary representation with one 1, getting 101. a(29) is the decimal equivalent of the result, which is 5.
%p A163509 := proc(n) bdgs := convert(n,base,2) ; while op(-1,bdgs) = op(-2,bdgs) do bdgs := subsop(-1=NULL,bdgs) ; od: add( op(d,bdgs)*2^(d-1),d=1..nops(bdgs) ) ; end: seq(A163509(n),n=1..120) ; # _R. J. Mathar_, Aug 07 2009
%t Table[FromDigits[Flatten[Join[{1},Rest[Split[IntegerDigits[n,2]]]]],2],{n,80}] (* _Harvey P. Dale_, Jul 17 2014 *)
%K base,look,nonn
%O 1,2
%A _Leroy Quet_, Jul 29 2009
%E More terms from _R. J. Mathar_, Aug 07 2009