A082087 - OEIS

A082087

a(n) is the fixed point if function A008472 (= sum of prime factors with no repetition) is iterated when started at initial value n!.

2, 5, 5, 7, 7, 17, 17, 17, 17, 3, 3, 41, 41, 41, 41, 31, 31, 5, 5, 5, 5, 7, 7, 7, 7, 7, 7, 5, 5, 7, 7, 7, 7, 7, 7, 197, 197, 197, 197, 2, 2, 281, 281, 281, 281, 43, 43, 43, 43, 43, 43, 7, 7, 7, 7, 7, 7, 5, 5, 5, 5, 5, 5, 5, 5, 73, 73, 73, 73, 2, 2, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 13, 13, 13, 13

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..85.

FORMULA

a(n) = A075860(A000142(n)).

EXAMPLE

n=73: iteration list=

{73!=61234458376886086861524070385274672740778091784697328983823014963978384987221689274204160000000000000000,639,74,39,16,2,2}

MATHEMATICA

ffi[x_] := Flatten[FactorInteger[x]] lf[x_] := Length[FactorInteger[x]] ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}] sopf[x_] := Apply[Plus, ba[x]] Table[FixedPoint[sopf, w! ], {w, 2, 100}]

CROSSREFS

Cf. A007504, A008472, A034387, A075860.

Sequence in context: A245083 A233565 A121359 * A263317 A256300 A342852

Adjacent sequences: A082084 A082085 A082086 * A082088 A082089 A082090

KEYWORD

nonn

AUTHOR

Labos Elemer, Apr 09 2003

STATUS

approved