LAS VEGAS — Las Vegas was buzzing for Major League Baseball on Monday night.The Athletics kicked off their first-ever Las Vegas Series with a slugfest against the Milwaukee Brewers, a 15-14 loss in 12 innings that marked the first MLB game in Sin City since 1996. The contest was the first of six the team will play at suburban Las Vegas Ballpark, home of its Triple-A affiliate, this week in an effort to introduce the club to the community before its move to a $2 billion-plus stadium on The Strip in 2028.Las Vegas welcomed the A’s in the only way it could. “Jersey Shore’s” DJ Pauly D and Backstreet Boy Nick Carter threw out ceremonial first pitches. Bruce Buffer announced the home starting lineup, with flames firing from portable torches positioned around the field after he howled each name. And fighter jets flew over as the final note of the national anthem rang. Not the typical environment for early-June baseball, especially for a sub-.500 team in the middling AL West.The ballpark was sold out, with 8,519 fans in attendance. Many adorned the free A’s jerseys handed out as they entered, each with “Vegas” and “28” sewn across the nameplate and number spot, respectively. But not all rooted for the home team. Cheers for the Brewers’ Jake Bauers after his first-inning RBI single rang loud through the stands and grew louder when Milwaukee catcher William Contreras mashed a three-run home run to take a four-run lead in the 10th inning. Roars for the A’s seven home runs, including two in the bottom of the inning to tie it, overpowered support for the Brewers, but the road team’s fans remained loud and active throughout the night.