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%I #21 Mar 09 2024 12:29:12
%S 1,21,31,421,521,631,731,8421,9421,10521,11521,12631,13631,14731,
%T 15731,168421,178421,189421,199421,2010521,2110521,2211521,2311521,
%U 2412631,2512631,2613631,2713631,2814731,2914731,3015731,3115731,32168421
%N Successive left concatenation of floor(k/2) beginning with n until we reach 1.
%C Every a(j) will divide some a(k), j < k. - _Robert G. Wilson v_, Mar 02 2002
%H Harvey P. Dale, <a href="/A068657/b068657.txt">Table of n, a(n) for n = 1..1000</a>
%e a(21) is constructed by starting with n, 21, then successively floor(21/2) = 10, floor(10/2) = 5, floor(5/2) = 2, floor(2/2) = 1, which is the end of the process of the halving. Now concatenate the results beginning with n: 21, 10, 5, 2, 1, which results in the number 2110521.
%p for m from 1 to 100 do a := m; n := m; while(n>1) do n := floor(n/2); if(n=1) then a := 10*a+1: else a := a*10^(ceil( log(n)/log(10)-0.000001) )+n:end if:end do:b[m] := a:end do:seq(b[i],i=1..100);
%t f[n_] := Floor[n/2]; Table[ ToExpression[ StringJoin[ ToString /@ Drop[ FixedPointList[f, n], -2]]], {n, 1, 35}]
%t Table[FromDigits[Flatten[IntegerDigits/@NestWhileList[Floor[#/2]&,n,#>1&]]],{n,40}] (* _Harvey P. Dale_, Mar 09 2024 *)
%K base,easy,nonn
%O 1,2
%A _Amarnath Murthy_, Feb 28 2002
%E More terms from _Sascha Kurz_, Mar 26 2002
%E Corrected by _Robert G. Wilson v_, Mar 02 2002
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