OFFSET
1,1
COMMENTS
From Gus Wiseman, Dec 01 2023: (Start)
Conjecture:
- The position of first appearance of k is n = A007097(k-2).
- The position of last appearance of k is n = A014221(k-2) = 2^^(k-2).
- The number of times k appears is: 1, 1, 2, 8, 435, ...
(End)
REFERENCES
Mohammad K. Azarian, On the Fixed Points of a Function and the Fixed Points of its Composite Functions, International Journal of Pure and Applied Mathematics, Vol. 46, No. 1, 2008, pp. 37-44. Mathematical Reviews, MR2433713 (2009c:65129), March 2009. Zentralblatt MATH, Zbl 1160.65015.
Mohammad K. Azarian, Fixed Points of a Quadratic Polynomial, Problem 841, College Mathematics Journal, Vol. 38, No. 1, January 2007, p. 60. Solution published in Vol. 39, No. 1, January 2008, pp. 66-67.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..1000
EXAMPLE
n=127:list={127,31,11,5,3,2,1,0},a[127]=8
MAPLE
f:= n-> add (numtheory[pi](i[1])*i[2], i=ifactors(n)[2]):
a:= n-> 1+ `if`(n=1, 1, a(f(n))):
seq (a(n), n=1..120); # Alois P. Heinz, Aug 09 2012
MATHEMATICA
ffi[x_] := Flatten[FactorInteger[x]] lf[x_] := Length[FactorInteger[x]] ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}] ep[x_] := Table[Part[ffi[x], 2*w], {w, 1, lf[x]}] bpi[x_] := Table[PrimePi[Part[ba[x], j]], {j, 1, lf[x]}] api[x_] := Apply[Plus, ep[x]*bpi[x]] Table[Length[FixedPointList[api, w]]-1, {w, 2, 128}]
Table[Length[FixedPointList[Total[PrimePi/@Join@@ ConstantArray@@@FactorInteger[#]]&, n]]-1, {n, 100}] (* Gus Wiseman, Dec 01 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Apr 09 2003
STATUS
approved