A049926 a(n)=a(1)+a(2)+...+a(n-1)-a(m), where m=n-1-2^p and 2^p<n-1<=2^(p+1).

1, 3, 3, 6, 10, 22, 42, 84, 165, 335, 668, 1336, 2669, 5334, 10656, 21292, 42542, 85167, 170332, 340664, 681325, 1362646, 2725280, 5450540, 10901038, 21801995, 43603820, 87207307, 174413946, 348826559, 697650453, 1395295584