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A109497
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Number of lucky numbers <= n.
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0
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1, 1, 2, 2, 2, 2, 3, 3, 4, 4, 4, 4, 5, 5, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 13, 13, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 17, 17, 17, 17, 18, 18, 19, 19, 19, 19, 20, 20
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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REFERENCES
| M. Gardner, Lucky numbers and 2187, Math. Intellig., 19 (No. 2, 1997), 26-29.
V. Gardiner, R. Lazarus, N. Metropolis and S. Ulam, On certain sequences of integers defined by sieves, Math. Mag., 29 (1955), 117-119.
R. K. Guy, Unsolved Problems in Number Theory, C3.
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LINKS
| MathWorld, Lucky Number
I. Peterson, MathTrek, Martin Gardner's Lucky Numbers
Wikipedia, Lucky Number
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EXAMPLE
| a(9)=4 because there are 4 lucky numbers less than or equal to 9 (1, 3, 7, 9)
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CROSSREFS
| Cf. A000959.
Sequence in context: A023193 A096605 A189671 * A156078 A123919 A194324
Adjacent sequences: A109494 A109495 A109496 * A109498 A109499 A109500
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KEYWORD
| nonn
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AUTHOR
| Shawn M. Moore (sartak(AT)gmail.com), Jun 30 2005
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