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A332737
Composite terms of A181659, where the sum of the iterated totient function attains a record.
0
289, 2329, 4369, 4913, 18769, 21331, 35209, 66049, 128881, 197143, 258121, 281929, 516961, 739903, 971203, 1762249, 1942663, 2070721, 2898703, 2952673, 3820819, 4142881, 8288641, 16773619, 16843009, 16974593, 20229241, 21762361, 32472241, 132575071, 187903693
OFFSET
1,1
COMMENTS
Most of the terms of A181659 are primes. Out of the first 10^4 terms of A181659 only 28 are composites.
The indices of the terms of this sequence in A181659 are 30, 73, 93, 99, 154, 161, 191, 236, 286, 316, ...
The corresponding record values (terms of A126106) are 527, 4223, 8191, 8847, 35527, 39423, 67583, 131327, 246869, 376559, 493739, 550911, 1009981, 1466879, 1884671, 3442687, 3819519, 4089245, 5707263, 5791743, 7444991, 8178491, 16464253, 33260031, 33554431, 33718527, 39989247, 42809067, 63932219, 263382015, 372697723.
MATHEMATICA
s[n_] := Plus @@ FixedPointList[EulerPhi, n] - n - 1; seq={}; smax = 1; Do[s1 =s[n]; If[s1 >smax, smax = s1; If[CompositeQ[n], AppendTo[seq, n]]], {n, 1, 5000}]; seq
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Feb 21 2020
STATUS
approved