This is makeindex, version 2.13 [07-Mar-1997] (using kpathsea).
Scanning input file 3k+1.idx....done (1 entries accepted, 0 rejected).
Sorting entries...done (0 comparisons).
Generating output file 3k+1.ind....done (5 lines written, 0 warnings).
Output written in 3k+1.ind.
Transcript written in 3k+1.ilg.
