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A048131 Becomes prime or 4 after exactly 9 iterations of f(x) = sum of prime factors of x. 1
4659, 5294, 5937, 9286, 10334, 10843, 15490, 16382, 17972, 18201, 18588, 18735, 19137, 19984, 20059, 22482, 23073, 23806, 25405, 26405, 26547, 27622, 27845, 28694, 28772, 30062, 30486, 31686, 32156, 32313, 33177, 33238, 33414, 33944 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
f(x) = sum of prime factors with multiplicity, so that f(1500) = 2+2+3+5+5+5 = 22.
LINKS
MATHEMATICA
sopf[n_]:=Total[Flatten[Table[#[[1]], #[[2]]]&/@FactorInteger[n]]]; nifQ[ n_]:=Length[NestWhileList[sopf, n, !PrimeQ[#]&&#!=4&]]==10; Select[ Range[ 4000, 34000], nifQ] (* Harvey P. Dale, Sep 06 2021 *)
CROSSREFS
Sequence in context: A069646 A159220 A020422 * A062626 A204489 A252127
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified May 24 03:56 EDT 2024. Contains 372771 sequences. (Running on oeis4.)