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A173662
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Triangle read by rows: R(n,k)= semiprime(n) mod semiprime(k), 0<k<=n.
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0
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0, 2, 0, 1, 3, 0, 2, 4, 1, 0, 2, 2, 5, 4, 0, 3, 3, 6, 5, 1, 0, 1, 3, 3, 1, 7, 6, 0, 2, 4, 4, 2, 8, 7, 1, 0, 1, 1, 7, 5, 11, 10, 4, 3, 0, 2, 2, 8, 6, 12, 11, 5, 4, 1, 0, 1, 3, 6, 3, 5, 3, 12, 11, 8, 7, 0, 2, 4, 7, 4
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OFFSET
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1,2
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COMMENTS
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Row sums are 0, 2, 4, 7, 13, 18, 28,...
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LINKS
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Table of n, a(n) for n=1..70.
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EXAMPLE
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0,
2,0;
1,3,0;
2,4,1,0;
2,2,5,4,0;
3,3,6,5,1,0;
1,3,3,1,7,6,0;
2,4,4,2,8,7,1,0;
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MATHEMATICA
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SemiprimeQ[n_Integer] := If[Abs[n]<2, False, (2==Plus@@Transpose[FactorInteger[Abs[n]]][[2]])]; sp = Select[Range[100], SemiprimeQ]; Flatten[Table[Mod[sp[[n]], sp[[Range[n]]]], {n, Length[sp]}]]
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CROSSREFS
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Cf. A001358, A173655.
Sequence in context: A219311 A022880 A128097 * A172026 A060318 A089994
Adjacent sequences: A173659 A173660 A173661 * A173663 A173664 A173665
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KEYWORD
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nonn,tabl,easy
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AUTHOR
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Juri-Stepan Gerasimov, Nov 28 2010
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EXTENSIONS
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46th term corrected by D. S. McNeil, Nov 24 2010
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STATUS
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approved
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