1,2

The divisors of 24 greater than 1 are the only positive integers n with the property m^2 == 1 (mod n) for all integer m coprime to n. - Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Jun 10 2001

n for which all Dirichlet characters are real. - Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 21 2002

These are the numbers n that are divisible by all numbers less than or equal to square root of n. - Tanya Khovanova (tanyakh(AT)yahoo.com), Dec 10 2006

Also, numbers n such that A160812(n) = 0. Also, numbers n such that A160813(n) = 0. - Omar E. Pol (info(AT)polprimos.com), Jun 19 2009

It appears that these are the only positive integers n such that A160812(n) = 0. [From Omar E. Pol (info(AT)polprimos.com), Nov 17 2009]

Harvey Cohn, "Advanced Number Theory", Dover, chap.II, p. 38

M. H. Eggar, A curious property of the integer 24, Math. Gazette, vol. 84, 2000, 96-97.

Eric Weisstein's World of Mathematics, Modulo Multiplication Group

a(n) = A161710(n-1). [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jun 21 2009]

(Other) sage: divisors(24); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 13 2009]

Sequence in context: A007886 A135108 A018515 this_sequence A160810 A143417 A018597

Cf. A160812, A160813. [From Omar E. Pol (info(AT)polprimos.com), Nov 17 2009]

Adjacent sequences: A018250 A018251 A018252 this_sequence A018254 A018255 A018256

nonn,fini,full,new

N. J. A. Sloane (njas(AT)research.att.com).