Please check why 183,187,189 in your list and you will find the answer.

100th element should be 471 though test expects 447. I dont understand. If algorithm was wrong earlier values would be wrong too. Here is my output for u(100). Can someone tell me whats the problem? Thanks
1,3,4,7,9,10,13,15,19,21,22,27,28,31,39,40,43,45,46,55,57,58,63,64,67,79,81,82,85,87,91,93,94,111,115,117,118,121,127,129,130,135,136,139,159,163,165,166,171,172,175,183,187,189,190,193,202,223,231,235,237,238,243,244,247,255,256,259,261,262,271,273,274,279,280,283,319,327,331,333,334,343,345,346,351,352,355,364,367,375,379,381,382,387,388,391,405,406,409,418,471,475,477,478,487,489,490,495,496,499,511,513,514,517,519,523,525,526,543,547,549,550,559,561,562,567,568,571,580,607,706,711,712,715,729,730,733,742,759,763,765,766,769,775,777,778,783,784,787,811,813,814,819,820,823,837,838,841,850,1066,1093,1135,1137,1138,1143,1144,1147,1161,1162,1165,1174,1215,1216,1219,1228,1255,1701,1702,1705,1714,1741,1822,2551

correct, they are same, order is not important. anyone worked with vectors would know that