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Search: id:A133837
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| A133837 |
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Semiprimes from partition of sequence of natural integers. |
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+0
1
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| 6, 4, 26, 9, 10, 65, 33, 57, 21, 22, 377, 111, 39, 123, 87, 91, 95, 49, 206, 339, 121, 62, 393, 69, 141, 145, 74, 1141, 362, 93, 94, 95, 291, 505, 209, 106, 215, 219, 111, 339, 115, 1205, 253, 917, 685, 566, 289, 146, 295, 299, 303, 933, 159, 321, 489, 835, 341
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Partition the sequence of natural integers into groups of numbers which sum up to semiprime: {1, 2, 3}, {4}, {5..8}, {9}, {10}, {11..15}, {16, 17}, {18..20}, {21}, {22}, {23..35}, {36..38}, {39}, {40..42}, {43, 44}, {45, 46}, {47, 48}, {49}, {50..53}, {54..59}, {60, 61}, {62}, {63..68}, {69}, {70, 71}, {72, 73}, {74}, {75..88}, {89..92}, {93}, {94}, {95}, {96..98}, {99..103}, etc. Corresponding semiprimes are: 6, 4, 26, 9, 10, 65, 33, 57, 21, 22, 377, 111, 39, 123, 87, 91, 95, 49, 206, 339, 121, 62, 393, 69, 141, 145, 74, 1141, 362, 93, 94, 95, 291, 505, etc.
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MATHEMATICA
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s=Range[300]; c=0; Label[1]; i=1; p=s[[1]]; While[i<Length[s]&&Plus@@Last/@FactorInteger[p]=/=2, i++; p=Plus@@Take[s, i]]; (*Print[{i, p}] ; *)c++; a[c]=p; s=Drop[s, i]; If[Length[s]>1, Goto[1]]; Table[a[j], {j, c}]
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CROSSREFS
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Sequence in context: A081631 A137174 A129886 this_sequence A121682 A038258 A114330
Adjacent sequences: A133834 A133835 A133836 this_sequence A133838 A133839 A133840
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Sep 26 2007
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