Perrin pseudoprime
Given the Perrin sequence, , , and for , if is not prime yet , that number is then called a Perrin pseudoprime
. The first few Perrin pseudoprimes are 271441, 904631, 16532714, 24658561, 27422714, 27664033, 46672291 (listed in A013998 of Sloane’s OEIS).
By itself this is not a good enough test of primality. Further requiring that and improves the test but not enough to be preferable to actually factoring out the number. The first few strong Perrin pseudoprimes are 27664033, 46672291, 102690901, 130944133, 517697641 (listed in A018187 of Sloane’s OEIS).
Unlike Perrin pseudoprimes, most other pseudoprimes (http://planetmath.org/PseudoprimeP) are because of a congruence relation
to a given base.