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Search: id:A073839
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| A073839 |
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Sum of the composite numbers between n and 2n (both inclusive). |
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+0
3
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| 0, 4, 10, 18, 33, 45, 53, 84, 94, 105, 138, 162, 201, 256, 272, 289, 340, 411, 431, 510, 532, 555, 624, 672, 747, 825, 853, 937, 1024, 1084, 1116, 1243, 1342, 1377, 1482, 1519, 1557, 1708, 1825, 1866, 1989, 2073, 2202, 2377, 2423, 2561, 2702, 2893, 2943
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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a(6) = 6 +8+9+10+12 = 45.
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MAPLE
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for n from 1 to 150 do l := 0:for j from n to 2*n do if not isprime(j) then l := l+j:fi:od:a[n] := l:od:a[1] := 0:seq(a[j], j=1..150);
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MATHEMATICA
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cs[x_] := Flatten[Position[Table[PrimeQ[j], {j, x, 2*x}], False]]+x-1; sucs[x_] := Apply[Plus, cs[x]]; Table[sucs[w], {w, 1, 128}]
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CROSSREFS
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Cf. A073840.
Sequence in context: A008011 A009867 A019455 this_sequence A009921 A050188 A062361
Adjacent sequences: A073836 A073837 A073838 this_sequence A073840 A073841 A073842
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Aug 13 2002
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EXTENSIONS
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More terms from Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de) and Labos E. (labos(AT)ana.sote.hu), Aug 14 2002
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