The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A327721 Dimension of quantum lens space needed for non-uniqueness. 0
 4, 6, 6, 4, 8, 6, 4, 6, 12, 4, 14, 8, 4, 6, 18, 4, 20, 6, 4, 12, 24, 4, 6, 14, 4, 6, 30, 4, 32, 6, 4, 18, 6, 4, 38, 20, 4, 6, 42, 4, 44, 6, 4, 24, 48, 4, 8, 6, 4, 6, 54, 4, 6, 6, 4, 30, 60, 4, 62, 32, 4, 6, 6, 4, 68, 6, 4, 6, 72, 4, 74, 38, 4, 6, 8, 4, 80, 6, 4, 42, 84, 4, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 3,1 COMMENTS a(n) is the dimension of the quantum lens space compared to the primary parameter n for the isomorphism class to depend on secondary parameters. In the literature the primary parameter is usually denoted by r. LINKS Peter Lunding Jensen, Frederik Ravn Klausen, Peter M. R. Rasmussen, Combinatorial classification of quantum lens spaces, arXiv:1701.04003 [math.OA], 2017; Pacific Journal of Mathematics, Vol. 297, No. 2, 12.2018, p. 339-365. FORMULA For n > 2, whenever 4 does not divide n we have a(n) = p + 1, where p is the smallest odd prime dividing n; and in the case 4 divides n we have a(n) = 4 whenever 3 divides n and a(n) = 6 otherwise. EXAMPLE a(8) = 6 since 4 divides 8 and no odd primes do. a(11) = 11+1 = 12 since the smallest odd prime dividing 11 is 11. a(12) = 4 since 3 and 4 both divide 12. PROG (PARI) a(n) = {if (n % 4,  my(f=factor(n)[, 1]~); if (f[1] % 2, f[1]+1, f[2]+1), if (n%3, 6, 4)); } \\ Michel Marcus, Sep 26 2019 CROSSREFS Sequence in context: A200352 A286720 A201393 * A327268 A146208 A011227 Adjacent sequences:  A327718 A327719 A327720 * A327722 A327723 A327724 KEYWORD nonn AUTHOR Frederik Ravn Klausen, Sep 23 2019 EXTENSIONS More terms from Michel Marcus, Sep 27 2019 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 28 06:29 EST 2020. Contains 331317 sequences. (Running on oeis4.)