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A123541
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a(0) = 2; for n > 0, a(n) = number of earlier terms which when added to n give a prime.
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5
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2, 1, 1, 1, 3, 1, 4, 1, 1, 2, 7, 2, 7, 1, 1, 4, 11, 3, 9, 2, 4, 4, 11, 0, 2, 4, 4, 11, 11, 6, 14, 2, 5, 7, 6, 8, 16, 10, 4, 15, 13, 9, 13, 10, 5, 9, 14, 5, 9, 9, 11, 10, 17, 6, 9, 11, 13, 19, 20, 11, 22, 8, 17, 14, 13, 14, 20, 13, 13, 22, 23, 9, 20, 8, 12, 16, 11, 13, 21, 13, 13, 16, 14, 12, 16, 15
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OFFSET
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0,1
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LINKS
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FORMULA
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MAPLE
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M:=100; a:=array(0..M); a[0]:=2; for n from 1 to M do t1:=0; for i from 0 to n-1 do if isprime(n+a[i]) then t1:=t1+1; fi; od: a[n]:=t1; od: [seq(a[n], n=0..M)];
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MATHEMATICA
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t={2}; Do[AppendTo[t, Length[Select[t+n, PrimeQ]]], {n, 2000}]; t (* T. D. Noe, Apr 30 2007 *)
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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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