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Search: id:A066680
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| A066680 |
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Badly sieved numbers: as in the Sieve of Eratosthenes multiples of unmarked numbers p are marked, but only up to p^2. |
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+0
9
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| 2, 3, 5, 7, 8, 11, 12, 13, 17, 18, 19, 23, 27, 29, 30, 31, 37, 41, 43, 45, 47, 50, 53, 59, 61, 63, 67, 70, 71, 73, 75, 79, 80, 83, 89, 97, 98, 101, 103, 105, 107, 109, 112, 113, 125, 127, 128, 131, 137, 139, 147, 149, 151, 154, 157, 163
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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A099104(a(n)) = 1.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics
Index entries for sequences generated by sieves
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EXAMPLE
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For 2, the first unmarked number, there is only one multiple <= 4=2^2:
giving 2 3 [4] 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 ...
for 3, the next unmarked number, we mark 6=2*3 and 9=3*3
giving 2 3 [4] 5 [6] 7 8 [9] 10 11 12 13 14 15 16 17 18 19 20 ...
for 5, the next unmarked number, we mark 10=2*5, 15=3*5, 20=4*5, and 25=5*5
giving 2 3 [4] 5 [6] 7 8 [9] [10] 11 12 13 14 [15] 16 17 18 19 [20] ... and so on.
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CROSSREFS
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Cf. A066681, A066682, A066683.
Cf. A099042, A099043.
Sequence in context: A100959 A026422 A026424 this_sequence A028780 A083028 A112929
Adjacent sequences: A066677 A066678 A066679 this_sequence A066681 A066682 A066683
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KEYWORD
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nonn,nice
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Dec 31, 2001
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