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A140490
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Trajectory of 1 under repeated application of the map: n -> n + third-smallest number that does not divide n.
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4
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1, 5, 9, 14, 19, 23, 27, 32, 38, 43, 47, 51, 56, 62, 67, 71, 75, 81, 86, 91, 95, 99, 104, 110, 116, 122, 127, 131, 135, 141, 146, 151, 155, 159, 164, 170, 176, 182, 187, 191, 195, 201, 206, 211, 215, 219, 224, 230, 236, 242, 247, 251, 255, 261, 266, 271, 275, 279, 284, 290, 296
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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MAPLE
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f:= proc(n) local k, count;
count:= 0;
for k from 2 do
if n mod k <> 0 then count:= count+1; if count = 3 then return n+k fi fi
od
end proc:
R:= 1: x:= 1:
for i from 1 to 100 do x:= f(x); R:= R, x od:
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MATHEMATICA
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NestList[#+Complement[Range[#+50], Divisors[#]][[3]]&, 1, 60] (* Harvey P. Dale, Apr 21 2022 *)
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PROG
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(PARI) third(n) = {my(nb = 0, k = 1); while (nb != 3, if (n % k, nb++); if (nb != 3, k++); ); k; }
f(n) = n + third(n);
lista1(nn) = {a = 1; print1(a, ", "); for (n=2, nn, newa = f(a); print1(newa, ", "); a = f(a); ); } \\ Michel Marcus, Oct 04 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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