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.
172081, 1773289, 4463641, 47006785, 295643089, 798770161, 1150270849, 1420379065, 1976295241, 18390744505, 122160500281, 134642101321, 215741809801, 228944441089, 263610459505, 321140603665, 374464040689, 444722065201, 676328168881, 1009514855521
Offset: 1
Keywords
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
Programs
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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;