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1, 4, 9, 18, 23, 48, 54, 60, 63, 77, 91, 92, 93, 104, 117, 126, 129, 137, 151, 152, 153, 167, 169, 214, 229, 239, 255, 256, 264, 266, 267, 270, 282, 285, 289, 293, 295, 297, 326, 342, 344, 345, 348, 350, 355, 364, 400, 420, 428, 436, 439, 440, 447, 454, 458
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OFFSET
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1,2
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COMMENTS
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Among first 1000 terms of A243625 there are 124 fixed points.
Almost certainly A243625 is a permutation of natural numbers.
And almost certainly there is no (easy) proof of it.
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LINKS
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MAPLE
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with(numtheory):
b:= proc(n) is(n=1) end: h:= 2:
g:= proc(n) option remember; global h; local k, t;
if n=1 then 1 else t:=g(n-1);
for k from h while b(k) or bigomega(t+k)<>2
do od; b(k):=true; while b(h) do h:=h+1 od; k
fi
end:
a:= proc(n) option remember; local k;
for k from 1+`if`(n=1, 0, a(n-1)) do
if g(k)=k then break fi
od: k
end:
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MATHEMATICA
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b[n_] := n == 1;
h = 2;
g[n_] := g[n] = Module[{k, t}, If[n == 1, 1, t = g[n - 1]; For[k = h, b[k] || PrimeOmega[t + k] != 2, k++]; b[k] = True; While[b[h], h++]; k]];
a[n_] := a[n] = Module[{k}, For[k = 1 + If[n == 1, 0, a[n - 1]], True, k++, If[g[k] == k, Break[]]]; k];
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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