1,2

"Somebody incorrectly remembered Fermat's little theorem as saying that the congruence a^{n+1} = a (mod n) holds for all a if n is prime" (Zagier). The sequence gives the set of integers n for which this property is in fact true.

If i = j (mod n), then m^i = m^j (mod n) for all m. The latter congruence generally holds for any (m, n)=1 with i = j (mod k), k being the order of m modulo n, i.e. the least power k for which m^k = 1 (mod n). - Lekraj Beedassy (blekraj(AT)yahoo.com), Jul 04 2002

J. Dyer-Bennet, "A Theorem in Partitions of the Set of Positive Integers", Amer. Math. Monthly, 47(1940) pp. 152-4.

D. Zagier, Problems posed at the St Andrews Colloquium, 1996

Sequence in context: A152479 A115961 A123137 this_sequence A054377 A007018 A100016

Adjacent sequences: A014114 A014115 A014116 this_sequence A014118 A014119 A014120

nonn,fini,full,nice

David Broadhurst (D.Broadhurst(AT)open.ac.uk)