The oligotm utility fails for primers >45 nt due to a linear nearest-neighbor approximation. For long amplicons (e.g., nanopore sequencing barcodes), use v2.5.0 or later.
Predicting if a primer will fold on itself (hairpins) or bind to its partner (dimers), which ruins the experiment [5, 15]. The Scientist’s Toolkit primer3 0.4.0