"Yo corro una vez por semana."
Translation:I run once a week.
My girlfriends family speaks Spanish but she still doesn't know every word. It depends on the culture of Spanish speakers and what English words they have adopted. For example my girlfriends mom didn't know emparedados she only knew sandwiches because of where she grew up and who she was surrounded by. But her father knew that word was sandwiches. So she does this to master the Spanish language, and maybe teach someone along the way.
They have the same meaning but I don't think it's the most suitable sentence in english. Just like you prefer saying "three times" over "thrice" you should prefer "once" over "one time".
If "once" and "one time" are interchangeable with no difference in register or meaning at all, then yes, it should be accepted.
Maybe it's the way Duolingo has to teach real equivalents and not just word per word translations.
My best guess would be the semantics of "Yo corro una vez por semana" implies a sort of, "I run regularly, about once a week." Whereas, "Yo corro una vez a la semana." implies a stricter ritual, "I run exactly once a week on this day, at this time."
But my only basis for that theory is the definite article making things more concrete, so please don't quote me. 8D
Yo corro vez por semana = I run time per week. The expression is "una vez" which means "once" [literally "one time"]. So translate 'once' as 'una vez'. You could switch out 'por semana' to 'a la semana' but you can't switch it out with 'una semana'. Even though we say in English "I run once a week."
The ”a” in “once a week” is actually a preposition, the same one that was added as a prefix to words like afoot, abed, ashore, aside, away, etc.
It’s not the same as the indefinite article a, so it doesn’t translate to «una», but rather it is very similar to the Spanish preposition «a».
Your sentence is not gramatically nor semantically correct. "Once a week" cannot translate as "una vez una semana", it doesn't make sense.
Once a week. Una vez por semana or una vez a la semana.
Also, 'semana' is feminine, so you can have 'la/una' before it but not 'el/un'. La semana, una semana