A109497 Number of lucky numbers <= n.

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

Offset

0,3

References

R. K. Guy, Unsolved Problems in Number Theory, C3.

Links

Table of n, a(n) for n=0..79.

V. Gardiner, R. Lazarus, N. Metropolis, and S. Ulam, On certain sequences of integers defined by sieves, Mathematics Magazine, 29(3) (1955), 117-122.

Martin Gardner, Lucky numbers and 2187, Math. Intellig., 19(2) (1997), 26-29.

I. Peterson, MathTrek, Martin Gardner's Lucky Numbers

Eric Weisstein's World of Mathematics, Lucky Number

Wikipedia, Lucky Number

Example

a(9)=4 because there are 4 lucky numbers less than or equal to 9 (1, 3, 7, 9)

Crossrefs

Cf. A000959.

Partial sums of A145649.

Sequence in context: A023193 A096605 A189671 * A156078 A123919 A194324

Adjacent sequences: A109494 A109495 A109496 * A109498 A109499 A109500

Keyword

nonn

Author

Shawn M. Moore (sartak(AT)gmail.com), Jun 30 2005

Status

approved