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A153513
Composite numbers k such that 2^k-2 and 3^k-3 are both divisible by k and k is not a Carmichael number (A002997).
8
2701, 18721, 31621, 49141, 83333, 83665, 88561, 90751, 93961, 104653, 107185, 176149, 204001, 226801, 228241, 276013, 282133, 534061, 563473, 574561, 622909, 653333, 665281
OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..200 from Robert Israel)
MAPLE
filter:= proc(n) local p;
if isprime(n) or (2 &^n - 2 mod n <> 0) or (3 &^n - 3 mod n <> 0) then return false fi;
if n::even then return true fi;
if not numtheory:-issqrfree(n) then return true fi;
for p in numtheory:-factorset(n) do
if n-1 mod (p-1) <> 0 then return true fi
od;
false
end proc:
select(filter, [$2..10^6]); # Robert Israel, Jan 29 2017
MATHEMATICA
Reap[Do[If[CompositeQ[n] && Divisible[2^n-2, n] && Divisible[3^n-3, n] && Mod[n, CarmichaelLambda[n]] != 1, Print[n]; Sow[n]], {n, 2, 10^6}]][[2, 1]] (* Jean-François Alcover, Mar 25 2019 *)
CROSSREFS
Intersection of A153514 and A153508 (excluding the number 1).
Sequence in context: A230752 A364795 A246888 * A333130 A214016 A254513
KEYWORD
nonn
AUTHOR
Artur Jasinski, Dec 28 2008
STATUS
approved