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 A331407 Numbers at which the sum of the iterated exponential totient function (A331273) attains a record. 2
 1, 2, 8, 32, 128, 864, 3456, 7776, 31104, 279936, 497664, 1990656, 4478976, 17915904, 62208000, 97200000, 559872000, 874800000, 1555200000, 6220800000, 13996800000, 55987200000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Analogous to A181659 with the exponential totient function (A072911) instead of the Euler totient function phi (A000010). The corresponding record values are 0, 1, 3, 5, 7, 11, 13, 19, 27, 37, 43, 51, 61, 75, 83, 101, 123, 147, 165, 195, 243, 293, ... LINKS MATHEMATICA ephi[n_] := Times @@ EulerPhi[FactorInteger[n][[;; , 2]]]; s[n_] := Plus @@ FixedPointList[ephi, n] - n - 1; seq = {}; smax = -1; Do[s1 = s[n]; If[s1 > smax, smax = s1; AppendTo[seq, n]], {n, 1, 5000}]; seq CROSSREFS Cf. A072911, A181659, A331273. Sequence in context: A081294 A004171 A009117 * A160637 A183895 A228921 Adjacent sequences:  A331404 A331405 A331406 * A331408 A331409 A331410 KEYWORD nonn,more AUTHOR Amiram Eldar, Feb 25 2020 STATUS approved

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Last modified August 14 07:59 EDT 2020. Contains 336477 sequences. (Running on oeis4.)