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 A329463 Carmichael numbers k such that sopf(k) is also a Carmichael number, where sopf(k) is the sum of the distinct primes dividing k (A008472). 1
 1618206745, 2265650401, 28645206001, 56969031001, 226244724265, 235389006721, 235771174081, 296423001601, 432133594201, 626086650961, 772165132201, 884500464001, 1167647270401, 4384350028801, 4714081284241, 5438971500481, 5916902791801, 7160462614273, 11458124974801 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS There are 1108 terms below 2^64: 75 have 5 prime factors, 1 have 7 prime factors (307696492063107001), and 1032 have 9 prime factors. The corresponding values of sopf(a(n)) are 1729, 1105, 1105, 1105, 115921, 2821, 2821, 2821, 15841, 2821, 1729, 10585, 2821, 2821, 75361, 2821, 15841, 2821, 334153, ... LINKS Amiram Eldar, Table of n, a(n) for n = 1..1108 EXAMPLE 1618206745 = 5 * 23 * 43 * 229 * 1429 is a Carmichael number, and 5 + 23 + 43 + 229 + 1429 = 1729 is also a Carmichael number. MATHEMATICA carmQ[n_] := CompositeQ[n] && Divisible[n - 1, CarmichaelLambda[n]]; sopf[n_] := Total[FactorInteger[n][[;; , 1]]]; s={}; Do[If[carmQ[n] && carmQ[sopf[n]], AppendTo[s, n]], {n, 2, 3*10^10}]; s CROSSREFS Cf. A002997, A008472. Sequence in context: A216905 A166383 A227444 * A246250 A126432 A186175 Adjacent sequences: A329460 A329461 A329462 * A329464 A329465 A329466 KEYWORD nonn AUTHOR Amiram Eldar, Nov 13 2019 STATUS approved

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Last modified December 7 19:19 EST 2022. Contains 358669 sequences. (Running on oeis4.)