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A210523 Record values of Dedekind psi function. 2
1, 3, 4, 6, 12, 18, 24, 36, 48, 72, 96, 108, 144, 168, 192, 216, 240, 288, 360, 384, 432, 576, 648, 672, 720, 864, 1008, 1152, 1296, 1344, 1440, 1728, 1800, 2016, 2304, 2592, 2880, 3024, 3456, 4032, 4320, 4608, 5184 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Record values of A001615.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..808 (terms 1..373 from Enrique Pérez Herrero)

FORMULA

a(n) = A001615(A330006(n)). - Amiram Eldar, Nov 26 2019

MAPLE

N:= 100: # to get a(1) to a(N)

A001615 := proc(n) n*mul((1+1/i[1]), i=ifactors(n)[2]) end:

count:= 0:

val:= -infinity:

for i from 1 while count < N do

  v:= A001615(i);

  if v > val then

     val:= v;

       count:= count+1;

       A[count]:=v;

  fi

od:

seq(A[i], i=1..N); # Robert Israel, Nov 19 2014

MATHEMATICA

JordanTotient[n_, k_:1] := DivisorSum[n, #^k*MoebiusMu[n/#]&] /; (n>0) && IntegerQ[n]; DedekindPsi[n_] := JordanTotient[n, 2]/EulerPhi[n]; a=1; lst={a}; Do[b=DedekindPsi[n]; If[b>a, a=b; AppendTo[lst, b]], {n, 2000}]; lst

psi[1] = 1; psi[n_] := n * Times @@ (1 + 1/FactorInteger[n][[;; , 1]]); seq = {}; pmax = 0; Do[pmax = psi[n]; If[p > pmax, pmax = p; AppendTo[seq, p]], {n, 1, 10^5}]; seq (* Amiram Eldar, Nov 26 2019 *)

CROSSREFS

Cf. A002183, A006093, A330006 (the corresponding positions of records).

Sequence in context: A293593 A024373 A111159 * A109069 A329953 A329671

Adjacent sequences:  A210520 A210521 A210522 * A210524 A210525 A210526

KEYWORD

nonn,changed

AUTHOR

Enrique Pérez Herrero, Jan 27 2013

STATUS

approved

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Last modified December 10 04:14 EST 2019. Contains 329885 sequences. (Running on oeis4.)