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A045997
Number of iterations required to reach stationary value when applying repeatedly applying d, the number of divisors function, to n!.
0
0, 0, 0, 3, 4, 3, 5, 6, 6, 6, 4, 6, 6, 6, 6, 6, 5, 6, 6, 6, 6, 6, 7, 6, 6, 6, 6, 5, 5, 7, 5, 6, 5, 6, 7, 5, 7, 6, 4, 6, 5, 7, 5, 5, 7, 7, 7, 7, 7, 7, 5, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 6, 7, 6, 7, 6, 7, 7, 7, 7, 7, 7, 6, 7, 7, 7, 7, 7, 7, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 6, 7, 6, 7, 7, 7, 6, 7
OFFSET
0,4
MATHEMATICA
Table[Length[FixedPointList[DivisorSigma[0, #]&, n!]]-2, {n, 0, 100}] (* Harvey P. Dale, May 19 2019 *)
PROG
(PARI) for(x=0, 100, for(a=0, 15, if(a==0, d=x!, if(d<3, print(a-1), d=numdiv(d) ))))
CROSSREFS
Sequence in context: A342927 A363013 A226798 * A360059 A262150 A325594
KEYWORD
nonn
STATUS
approved