l1 = list(integer(0), 11L, integer(0), integer(0), 11L, 11L, c(6L,
36L), 16L, 16L, integer(0), integer(0))

df = data_frame(entry = c(2, 5, 6, 7, 7, 8, 9), element = c(11, 11, 11, 6,
36, 16, 16))

setNames(l1, seq_along(l1)) %>% enframe %>% unnest

stack(setNames(l1, seq_along(l1)))