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!)
 A277720 Numbers n > 2 such that lambda(n)^2 divides n-1, where lambda(n) = A002322(n). 0
 2320690177, 17069520863233, 42182344790209, 65465530560001, 3432376805760001, 13322002122777601, 20388795375960001, 129009714848870401, 580007888606160001, 1096591987029196801, 3029756968906340401, 5806765663003468801, 6213994663149504001, 6367205158826803201, 7802569551798000001, 10319507991273499201 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Squarefree numbers n > 2 such that (p-1)^2 | n-1 for every prime p|n. For the first five terms, lambda(n)^2 | phi(n). - Thomas Ordowski, Apr 11 2017 LINKS PROG (PARI) isok(n) = (n % lcm(znstar(n)[2])^2)  == 1; \\ Michel Marcus, Apr 22 2017 CROSSREFS Subsequence of A002997 and of A277389. Cf. A002322. Sequence in context: A225760 A022240 A251490 * A090875 A132907 A038685 Adjacent sequences:  A277717 A277718 A277719 * A277721 A277722 A277723 KEYWORD nonn AUTHOR Thomas Ordowski and Charles R Greathouse IV, Oct 28 2016 EXTENSIONS a(7)-a(16) from Max Alekseyev, Apr 23 2017 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 March 28 05:38 EDT 2020. Contains 333073 sequences. (Running on oeis4.)