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 A328939 Carmichael numbers that are products of primes p for which each p-1 is squarefree. 1
 10267951, 72108421, 111291181, 139952671, 1588247851, 6004532941, 7200256261, 8815102297, 9001235881, 10884042841, 15989367241, 18500666251, 23729234761, 34268731321, 34558584607, 37870128451, 74689102411, 77538554731, 121254376891, 149842746691, 187054437571 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Shanks noted that among the first 300 Carmichael numbers only 3 are in this sequence. LINKS Amiram Eldar, Table of n, a(n) for n = 1..2843 (terms below 2^64) Paul ErdÅ‘s, On pseudoprimes and Carmichael numbers, Publ. Math. Debrecen 4 (1956), pp. 201-206. Andrew Granville and Carl Pomerance, Two contradictory conjectures concerning Carmichael numbers, Mathematics of Computation, Vol. 71, No. 238 (2002), pp. 883-908. Daniel Shanks, Solved and Unsolved Problems in Number Theory, 2nd ed., Chelsea Pub. Co., New York, 1978, p. 229. MATHEMATICA aQ[n_] := CompositeQ[n] && Divisible[n-1, CarmichaelLambda[n]] && AllTrue[FactorInteger[n][[;; , 1]] - 1, SquareFreeQ]; Select[Range[10^8], aQ] CROSSREFS Cf. A002997. Sequence in context: A109179 A030093 A188755 * A234062 A235723 A118213 Adjacent sequences:  A328936 A328937 A328938 * A328940 A328941 A328942 KEYWORD nonn AUTHOR Amiram Eldar, Oct 31 2019 STATUS approved

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Last modified January 27 06:18 EST 2022. Contains 350601 sequences. (Running on oeis4.)