It's not 16 notes but three notes. C B A. The first note is repeated for a measure, the second is repeated for a half note, and the third is played once. Yes, it's undoubtedly a coincidence. See https://i.cbc.ca/1.5235857.1564861522!/fileImage/httpImage/i...
the repetition is super important. in modern music the rhythm is more important than the variety of tones. the same rhythm and the same tonal distance is too big to be a coincidence
Technically, it's enormous, maybe 8^15 possible melodies.
But what about good-sounding melodies? That drastically reduces the space.
What about memorable, good-sounding melodies? Most melodies aren't catchy, so that limits the space some more.
What about culturally-appropriate, memorable, good-sounding melodies? It likely wouldn't make sense to use a Turkish opera melody in a pop song. Genres typically encompass a small space of melodies (e.g. Blues, Boogie Woogie).
What about such melodies that follow a particular rhythm, or match the vocalist's range, or that follow a desired chord progression?
After all this is considered, you're probably down to only a million combinations. But there are a billion songs out there...
the range of notes in pentatonic scale is only five. but the rhythms (the important part of modern music) have a lot more combinations. katy perry's writers used the exact same rhythm with the same notes, which is highly improbable
I'm not really familiar with either song, but I do think it could be a coincidence. From a Music Theory perspective, they both appear to be in the key C (suddenly we're down to eight notes) and both in 4/4 time. Unfortunately the changes (chord progressions) aren't there but if this rests on melodic similarities then it's not hard for there to be similarities.
i am actually a musician, the rhythm is important and a sequence of 16 notes at the same rhythm and the same tonal distance is too big to be a coincidence