%I
%S 1,3,2,5,7,9,11,4,6,8,13,15,17,19,21,23,10,12,14,16,18,25,27,29,31,33,
%T 35,37,39,20,22,24,26,28,30,32,41,43,45,47,49,51,53,55,57,59,34,36,38,
%U 40,42,44,46,48,50
%N 2n odd numbers followed by 2n1 even numbers.
%t Riffle[TakeList[2*Range[100]1,2*Range[9]],TakeList[ 2*Range[100],2*Range[ 0,9]+1]] // Flatten (* _Harvey P. Dale_, Mar 01 2018 *)
%o (PARI) lista(nn) = {curo = 1; cure = 2; for (n = 1, nn, for (i = 1, 2*n, print1(curo, ", "); curo += 2;); for (i = 1, 2*n  1, print1(cure, ", "); cure += 2;););} \\ _Michel Marcus_, Sep 16 2013
%K easy,nonn
%O 1,2
%A _Amarnath Murthy_, Jul 20 2005
