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Search: id:A110261
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| A110261 |
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Number of distinct numbers that can be written as floor(n/i)+floor(n/j), 1<=i<=j<=n. |
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+0
5
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| 1, 3, 3, 6, 6, 9, 9, 10, 12, 13, 13, 16, 16, 17, 17, 20, 20, 21, 21, 24, 24, 25, 25, 26, 28, 29, 29, 30, 30, 33, 33, 34, 34, 35, 34, 38, 38, 39, 39, 40, 40, 43, 43, 44, 45, 44, 44, 45, 48, 48, 50, 50, 50, 51, 51, 54, 55, 54, 54, 55, 55, 56, 57, 60, 60, 61, 61, 62, 62, 61, 61, 65
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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a(p) = a(p-1) for odd primes p;
the sequence is not monotonically increasing, see A110264 for numbers m with a(m)<a(m-1);
a(m)<a(A110262(n)) for m<A110262(n), a(A110262(n))=A110263(n);
A110265(n) = (smallest number <> floor(n/i)+floor(n/j), 1<=i<=j<=n).
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EXAMPLE
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a(10) = #{20,15,13,12,11,10,8,7,6,5,4,3,2} = 13:
20=10/1+10/1, 15=10/1+10/2, 13=10/1+[10/3], 12=10/1+10/5,
11=10/1+[10/6], 10=10/2+10/2, 8=10/2+[10/3], 7=10/2+10/5, 6=10/2+[10/6],
5=[10/3]+10/5, 4=10/5+10/5, 3=10/5+[10/6] and 2=[10/6]+[10/6].
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CROSSREFS
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Sequence in context: A023842 A165885 A061795 this_sequence A049318 A079551 A008805
Adjacent sequences: A110258 A110259 A110260 this_sequence A110262 A110263 A110264
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jul 18 2005
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