This is cutadapt 2.10 with Python 3.6.7 Command line parameters: -j 1 -a AGATCGGAAGAGC -u 10 -u -10 -q 20 -m 30 -O 3 -o fastq/zr1394_18_s456.fastq.gz zr1394_18_s456.fastq.gz Processing reads on 1 core in single-end mode ... Finished in 1104.72 s (20 us/read; 3.02 M reads/minute). === Summary === Total reads processed: 55,559,681 Reads with adapters: 850,679 (1.5%) Reads written (passing filters): 46,239,101 (83.2%) Total basepairs processed: 2,797,597,463 bp Quality-trimmed: 14,326,045 bp (0.5%) Total written (filtered): 1,423,191,630 bp (50.9%) === Adapter 1 === Sequence: AGATCGGAAGAGC; Type: regular 3'; Length: 13; Trimmed: 850679 times No. of allowed errors: 0-9 bp: 0; 10-13 bp: 1 Bases preceding removed adapters: A: 26.8% C: 1.1% G: 29.9% T: 42.2% none/other: 0.0% Overview of removed sequences length count expect max.err error counts 3 582227 868120.0 0 582227 4 231283 217030.0 0 231283 5 11914 54257.5 0 11914 6 10637 13564.4 0 10637 7 3928 3391.1 0 3928 8 911 847.8 0 911 9 2641 211.9 0 859 1782 10 4743 53.0 1 132 4611 11 2071 13.2 1 39 2032 12 270 3.3 1 0 270 13 44 0.8 1 0 44 14 3 0.8 1 0 3 16 7 0.8 1 0 7