library(purrr)

map2(1:3, 1:3, fn)

[[1]]
  res  text
1   1     a
2   1     b
3   2 total

[[2]]
  res  text
1   2     a
2   2     b
3   4 total

[[3]]
  res  text
1   3     a
2   3     b
3   6 total

x <- mapply(fn, b = 1:3, a = 1:3, SIMPLIFY = F)

x <- Map(fn, b = 1:3, a = 1:3)