A007324 - OEIS

A007324

Least number for which Solovay-Strassen primality test on bases < prime(n) fails.
(Formerly M5443)

9, 561, 1729, 1729, 399001, 399001, 1857241, 1857241, 6189121, 14469841, 14469841, 14469841, 86566959361, 311963097601, 369838909441, 6389476833601, 6389476833601, 8493512837546881, 10120721237827201, 10120721237827201, 91230634325542321

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Alejandra Alcantarilla Sanchez, Table of n, a(n) for n = 1..35

Alejandra Alcantarilla Sánchez, Looking at Solovay-Strassen as an Adversary: A study on pseudoprime construction, Bachelor's Thesis, Eindhoven Univ. Tech. (Netherlands 2025). See p. 97, Table F.2.

Wikipedia, Solovay-Strassen primality test.

PROG

(PARI) a(n) = my(b, p=factorback(primes(n-1))); forcomposite(k=9, oo, if(gcd(k, p)==1, b=2; while(Mod(b, k)^(k\2) == kronecker(b, k), b++); if(b>=prime(n), return(k)))); \\ Jinyuan Wang, Jun 04 2022

CROSSREFS

Cf. A083876, A271221, A329726.

Sequence in context: A357229 A267548 A326614 * A354692 A373882 A347844

Adjacent sequences: A007321 A007322 A007323 * A007325 A007326 A007327

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Eric Bach (bach(AT)cs.wisc.edu)

EXTENSIONS

Offset changed to 1 and a(1) corrected by Jinyuan Wang, Jun 04 2022

a(13) onward from Alejandra Alcantarilla Sanchez, Dec 15 2025

STATUS

approved