The Washington Federals, riding a wave of Redskins mania, say their season-ticket sales have soared in the last few weeks and that they expect to have sold 17,000 or 18,000 by their opening U.S. Football League game March 6.

Berl Bernhard, chairman and chief executive officer of the Federals, said the club already has sold more than 13,000 season tickets, well ahead of projections, and that sales are continuing at a rate of 225 per day for the team's nine home games at RFK Stadium.

The 13,000 season tickets sold place the Federals fifth among the league's 12 teams.

"Whether it's Redskins fever or just football fever, we're delighted with it in any event," said Bernhard. "The really surprising thing was the week before the Dallas game when we thought we might have some difficulty. We broke all records and sold 1,200 tickets. We're more than satisfied with the progress."

Bernhard said if season-ticket sales continue at the present rate, the final number will be around 18,000.

"The pace has become rather frantic," Bernhard said. "The delight we've all felt about the Redskins winning the championship is infectious. People who have been unable to get playoff tickets or Redskin tickets want football, and we seem to be the beneficiaries."

George McFadden, director of public relations for the USFL, said season-ticket sales throughout the league are ahead of projections, although there is substantial variance from city to city.

The Denver Gold has sold the most, 30,000 season tickets. The Denver Broncos of the National Football League led the NFL in average home attendance this year, 73,911 per game despite a losing season.

In Oakland, where fans have been without pro football since the NFL's Raiders left for Los Angeles before the start of last season, the USFL's Invaders have sold 20,000 season tickets, and a spokesman said the team hopes to sell 30,000 before the season begins.

The only other USFL teams to have sold more season tickets than Washington, according to the league, are the Tampa Bay Bandits, 18,000, and the New Jersey Generals, 14,000. Other figures: Arizona Wranglers and Chicago Blitz, 12,000 each; Los Angeles Express, 10,000; Philadelphia Stars, 9,000; Birmingham Stallions, 8,000; Michigan Panthers, 4,500, and the Boston Breakers, 3,000.

McFadden said the Breakers were late getting started on their marketing program because they only recently decided their home games would be played at Boston University's stadium.