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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A242980 Carmichael numbers of the form (6*k + 1)*(12*k + 1)*(18*k + 1), where only two of the three numbers 6*k + 1, 12*k + 1, 18*k + 1 are prime. 3
172081, 1773289, 4463641, 47006785, 295643089, 798770161, 1150270849, 1420379065, 1976295241, 18390744505, 122160500281, 134642101321, 215741809801, 228944441089, 263610459505, 321140603665, 374464040689, 444722065201, 676328168881, 1009514855521 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..2665 (terms < 4*10^30)

Carlos Rivera, Puzzle 739

Eric Weisstein's World of Mathematics, Carmichael Number

Index entries for sequences related to Carmichael numbers

PROG

(MAGMA) lst:=[]; for k in [1..920] do t:={n: n in [1..3] | IsPrime(6*k*n+1)}; if #Set(t) eq 2 then c:=&*[6*k*n+1: n in [1..3]]; if IsOne(c mod CarmichaelLambda(c)) then lst:=Append(lst, c); end if; end if; end for; lst;

CROSSREFS

Cf. A002997, A033502, A242981.

Sequence in context: A206115 A204730 A049053 * A221742 A239789 A233488

Adjacent sequences:  A242977 A242978 A242979 * A242981 A242982 A242983

KEYWORD

nonn

AUTHOR

Arkadiusz Wesolowski, May 28 2014

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 22 18:45 EDT 2021. Contains 348175 sequences. (Running on oeis4.)