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A246520 Largest number that can be written in binary as concatenation of (n - k) and (n + k), 0 <= k <= n.

%I A246520 #12 May 22 2025 10:21:40
%S A246520 0,3,10,20,36,45,72,104,136,153,170,208,272,336,400,464,528,561,594,
%T A246520 627,660,693,800,928,1056,1184,1312,1440,1568,1696,1824,1952,2080,
%U A246520 2145,2210,2275,2340,2405,2470,2535,2600,2665,2730,2880,3136,3392,3648,3904
%N A246520 Largest number that can be written in binary as concatenation of (n - k) and (n + k), 0 <= k <= n.
%C A246520 Largest term in row n of A246830.
%H A246520 Reinhard Zumkeller, <a href="/A246520/b246520.txt">Table of n, a(n) for n = 0..1000</a>
%t A246520 Table[Max[FromDigits[#,2]&/@Table[Join[IntegerDigits[n-k,2],IntegerDigits[ n+k,2]],{k,0,n}]],{n,0,50}] (* _Harvey P. Dale_, Oct 02 2018 *)
%o A246520 (Haskell)
%o A246520 a246520 = maximum . a246830_row
%o A246520 (Python)
%o A246520 def A246520(n):
%o A246520     return(max(int(bin(n-k)[2:]+bin(n+k)[2:],2) for k in range(n+1)))
%o A246520 # _Chai Wah Wu_, Sep 07 2014
%Y A246520 Cf. A246830, A007088, A246701 (first dfferences).
%K A246520 nonn,base
%O A246520 0,2
%A A246520 _Reinhard Zumkeller_, Sep 04 2014