This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A065703 Values of m such that N = (m+1)(2m+1)(71m+1) is a Carmichael number. 9
 1170, 5430, 53568, 54678, 59106, 63366, 86370, 95316, 99576, 103836, 105966, 116190, 183498, 184776, 239730, 260178, 300648, 319818, 333450, 339840, 362418, 367530, 481698, 485958, 503850, 511518, 605238, 644856 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS FORMULA "m+1, 2m+1, 71m+1 are primes and m|(N-1), 2m|(N-1), 71m|(N-1)" is a sufficient, but not necessary condition. [Corrected by  M. F. Hasler, Aug 23 2012] EXAMPLE For m=54678 the formula yields a Carmichael number with 5 prime factors. - M. F. Hasler, Aug 23 2012 MATHEMATICA CarmichaelNbrQ[n_] := ! PrimeQ@ n && Mod[n, CarmichaelLambda@ n] == 1; Select[ Range@ 1000000, PrimeQ[# + 1] && PrimeQ[2# + 1] && PrimeQ[71# + 1] && CarmichaelNbrQ[(# + 1)(2# + 1)(71# + 1)] &] (* Robert G. Wilson v, Aug 23 2012 *) PROG (PARI) for(m=1, 1e6, is_A002997((m+1)*(2*m+1)*(71*m+1)) & print1(m", "))  \\ - M. F. Hasler, Aug 23 2012 CROSSREFS Cf. A064238-A064262, A065695, A065696, A065697, A065698, A065699, A065700, A065701, A065702. Sequence in context: A209825 A264688 A043432 * A202487 A230946 A225234 Adjacent sequences:  A065700 A065701 A065702 * A065704 A065705 A065706 KEYWORD nonn AUTHOR Harvey Dubner (harvey(AT)dubner.com), Nov 14 2001 EXTENSIONS Definition simplified, missing terms inserted, and extended by M. F. Hasler, Aug 23 2012 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 July 21 06:55 EDT 2019. Contains 325192 sequences. (Running on oeis4.)