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_7_s456.fastq.gz zr1394_7_s456.fastq.gz Processing reads on 1 core in single-end mode ... Finished in 993.94 s (20 us/read; 3.04 M reads/minute). === Summary === Total reads processed: 50,399,353 Reads with adapters: 761,127 (1.5%) Reads written (passing filters): 41,373,003 (82.1%) Total basepairs processed: 2,532,578,583 bp Quality-trimmed: 13,546,792 bp (0.5%) Total written (filtered): 1,273,184,778 bp (50.3%) === Adapter 1 === Sequence: AGATCGGAAGAGC; Type: regular 3'; Length: 13; Trimmed: 761127 times No. of allowed errors: 0-9 bp: 0; 10-13 bp: 1 Bases preceding removed adapters: A: 26.6% C: 1.1% G: 29.1% T: 43.2% none/other: 0.0% Overview of removed sequences length count expect max.err error counts 3 517451 787489.9 0 517451 4 206778 196872.5 0 206778 5 11738 49218.1 0 11738 6 10881 12304.5 0 10881 7 4321 3076.1 0 4321 8 968 769.0 0 968 9 2351 192.3 0 831 1520 10 4566 48.1 1 122 4444 11 1784 12.0 1 43 1741 12 237 3.0 1 1 236 13 31 0.8 1 0 31 14 6 0.8 1 0 6 15 1 0.8 1 0 1 16 4 0.8 1 0 4 17 5 0.8 1 0 5 18 2 0.8 1 0 2 19 2 0.8 1 0 2 20 1 0.8 1 0 1