For Colorado, 13 truly is an unlucky number.The Buffs’ 71-59 loss Tuesday night at No. 17 Kansas was their 13th straight, all in Big 12 Conference play. They look to get into the win column in Boulder on Saturday when UCF arrives in Boulder for another Big 12 contest.A poor first half did Colorado (9-15, 0-13 Big 12) in as it was outscored 40-26 by the Jayhawks. There was good news in the latest setback, though, as freshman Sebastian Rancik scored a career-high 19 points on 7-of-13 shooting while also grabbing nine rebounds.”He’s got toughness, he’s not afraid and he’s going to keep getting better and better,” Buffs coach said Tad Boyle after Tuesday night’s defeat. “Sebastian played well at times tonight on the offensive end.”Offense has been a recurring issue with Colorado. It ranks 277th in Division I at 70.2 points per game and averages 14.7 turnovers a game, which is a dismal 340th out of 364 Division I programs. And on the rare nights when it takes care of the ball, as was the case at Kansas when it had just eight miscues, it seems to shoot poorly.The Buffs made 22 of 57 from the field Tuesday, including 4 of 23 from 3-point range. Leading scorer Julian Hammond III (13.2 ppg) was just 1 of 7 from the field in that loss.