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%I #9 Feb 18 2021 02:36:28
%S 2,3,8,12,18,27,32,48,72,108,128,162,192,243,288,432,512,648,768,972,
%T 1152,1458,1728,2048,2187,2592,3072,3888,4608,5832,6912,8192,8748,
%U 10368,12288,13122,15552,18432,19683,23328,27648,32768,34992,41472,49152,52488
%N Numbers of the form, 2^i*3^j, i+j odd.
%H Reinhard Zumkeller, <a href="/A257999/b257999.txt">Table of n, a(n) for n = 1..10000</a>
%F A069352(a(n)) mod 2 = 1.
%F Sum_{n>=1} 1/a(n) = 5/4. - _Amiram Eldar_, Feb 18 2021
%t max = 53000; Reap[Do[k = 2^i*3^j; If[k <= max && OddQ[i + j], Sow[k]], {i, 0, Log[2, max] // Ceiling}, {j, 0, Log[3, max] // Ceiling}]][[2, 1]] // Union (* _Amiram Eldar_, Feb 18 2021 after _Jean-François Alcover_ at A036667 *)
%o (Haskell)
%o a257999 n = a257999_list !! (n-1)
%o a257999_list = filter (odd . flip mod 2 . a001222) a003586_list
%Y Complement of A036667 with respect to A003586.
%Y Intersection of A026424 and A003586.
%Y Cf. A069352, A022328, A022329.
%K nonn
%O 1,1
%A _Reinhard Zumkeller_, May 16 2015
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