The interesting format for this weekend’s trio of Buffalo Philharmonic Orchestra Classics Series concerts finds the world premiere of an unusual Triple Trombone Concerto flanked by two of the most popular symphonies in the repertoire.

Prokofiev’s 1917 “Classical” Symphony is a delightful but deceptively difficult work. The flutes’ articulation was sluggish at the start and the slow movement was perfunctory, but the proper lightness infused the charming Gavotte movement and Music Director JoAnn Falletta’s brisk tempo gave an exciting lift to the Finale.

The centerpiece was the premiere of Eric Ewazen’s “Triple Trombone Concerto,” featuring the BPO’s tenor trombonists Jonathan Lombardo and Timothy Smith, and bass trombonist Jeffrey Dee.

The trombone is an important orchestral instrument, but is not familiar in solo context. Ardent concertgoers might remember the glowingly intense trombone solo in Sibelius’ Symphony No. 7, and may once have heard Rimsky-Korsakov’s Trombone Concerto. Therefore it was tempting to call this work unique, but an Internet search found a few other concertos for three trombones. Unique, no, but it is certainly unusual. And on first exposure, its outstanding feature seems to be the glorious sonority three trombones can produce.

In the usual three movements, the first is a smooth-textured development of three main themes that gradually increases in tension and tempo, reaching the “allegro energico” level. Ewazen’s style is lyrical and conservative, no more radical than, say, Copland. He uses the full orchestra in subdued but interestingly voiced passages and percussion sprinkled support. The three trombones carry most of the load in this journey, primarily speaking as a single harmonized voice, with occasional passages in easy counterpoint, the first movement peaking in a blazing fortissimo cutoff.

The composer describes the Finale as “rip-roaring.” He’s right. It was similar in spirit to the first movement but much more blazing and aggressive.

The very moving slow movement was dedicated to the late Scott Parkinson, former BPO principal trombone, who died unexpectedly in 2004. It’s a work of extreme warmth and affection, introduced sequentially by the three soloists and building in a conversational way to proclamations in a rich, chorale-like ambience. The closing measures are punctuated by discreet orchestra bell tones, but the lingering memory is the way the music revels in the rich sonority three trombones can produce. It was almost like the ultimate extrapolation of the kind of mellow harmonies many of us first experienced in barbershop quartet singing.

The concert concluded with Beethoven’s Symphony No. 7. It was solid and assertive, with the incomparable slow movement’s solemnity and inexorable tread coming through very movingly. The finale’s surging and intoxicating thrust validated Wagner’s statement that it is the “apotheosis of the dance.” It was a fine performance.