$ 
for sequence in */sequence.md
do
(
cd $(dirname $sequence)
pandoc --verbose --from markdown --to pdf --output sequence.pdf sequence.md
)
done
pdftk */sequence.pdf cat output sequences.pdf
pandoc: sequence.md: withBinaryFile: does not exist (No such file or directory)
HasCallStack backtrace:
  collectBacktraces, called at libraries/ghc-internal/src/GHC/Internal/Exception.hs:169:13 in ghc-internal:GHC.Internal.Exception
  toExceptionWithBacktrace, called at libraries/ghc-internal/src/GHC/Internal/IO.hs:260:11 in ghc-internal:GHC.Internal.IO
  throwIO, called at libraries/ghc-internal/src/GHC/Internal/IO/Exception.hs:315:19 in ghc-internal:GHC.Internal.IO.Exception
  ioException, called at libraries/ghc-internal/src/GHC/Internal/IO/Exception.hs:319:20 in ghc-internal:GHC.Internal.IO.Exception


Error: Unable to find file.
Error: Failed to open input PDF file: 
   */sequence.pdf
Errors encountered.  No output created.
Done.  Input errors, so no output created.