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Search: id:A078435
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| A078435 |
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Number of composites <= n^2. |
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+0
4
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| 1, 2, 5, 10, 16, 25, 34, 46, 59, 75, 91, 110, 130, 152, 177, 202, 228, 258, 289, 322, 356, 392, 430, 471, 511, 554, 600, 647, 695, 746, 799, 852, 908, 965, 1025, 1086, 1150, 1216, 1281, 1349, 1418, 1490, 1566, 1641, 1719, 1797, 1880, 1962, 2044, 2133, 2223
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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a(n)=n^2-A038107(n). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 22 2009]
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EXAMPLE
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a(3)=5 because the only composites <= 9 are 1, 4, 6, 8 and 9.
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MAPLE
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NumComposites := proc(N::posint) local count, i:count := 0:for i from 1 to N do if not isprime(i) then count := count + 1 fi:od: count; end:seq(NumComposites(k^2), k=1..51); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 26 2008
A038107 := proc(n) numtheory[pi]( n^2) ; end: A078435 := proc(n) n^2-A038107(n) ; end: seq(A078435(n), n=1..100) ; [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 22 2009]
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CROSSREFS
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Sequence in context: A084587 A001859 A011903 this_sequence A049815 A047992 A079984
Adjacent sequences: A078432 A078433 A078434 this_sequence A078436 A078437 A078438
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KEYWORD
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nonn
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AUTHOR
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John E. Lenz (jel5010(AT)yahoo.com), Dec 30 2002
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