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2, 3, 5, 3, 3, 2, 5, 5, 5, 2, 3, 3, 2, 3, 7, 5, 3, 7, 5, 3, 5, 3, 7, 3, 7, 5, 3, 3, 5, 5, 3, 5, 3, 7, 7, 5, 5, 7, 5, 3, 5, 7, 7, 3, 5, 3, 3, 5, 5, 3, 3, 7, 3, 3, 5, 3, 5, 7, 3, 5, 7, 3, 3, 5, 11, 3, 5, 5, 5, 3, 5, 5, 5, 5, 7, 3, 7, 5, 5, 7, 3, 5, 5, 3, 3, 5, 3, 7, 7, 5
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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a(n) <= 17 for n <= 250000 (see A251543).
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LINKS
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EXAMPLE
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A098550(n) for n= 1..11 is 1,2,3,4,9,8,15,14,5,6,25. Each time you see a prime, divide the term two steps ahead by that prime. The result is 4/2=2, 9/3=3, 25/5=5,...
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MATHEMATICA
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max = 1200;
f[lst_] := Block[{k = 4}, While[GCD[lst[[-2]], k] == 1 || GCD[lst[[-1]], k] > 1 || MemberQ[lst, k], k++]; Append[lst, k]];
A098550 = Nest[f, {1, 2, 3}, max - 3];
sel = Select[Transpose[{Range[max], A098550}], PrimeQ[#[[2]]]&][[All, 1]]+2;
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PROG
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(Haskell)
a251542 n = a251542_list !! (n-1)
a251542_list = [div u v | (u, v) <- zip(drop 2 a098550_list) a098550_list,
a010051' v == 1]
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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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