

A111654


n appears nth composite number times.


4



1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9
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OFFSET

1,5


REFERENCES

T. M. Apostol, Introduction to Analytic Number Theory, SpringerVerlag, 1976, page 2.
J. B. Rosser and L. Schoenfeld, Approximate formulas for some functions of prime numbers, Illinois J. Math. 6: 6494 (1962).
L. Panaitopol, Some Properties of the Series of Composed [Composite] Numbers, J. Inequalities in Pure and Applied Mathematics. 2(2): Article 38, 2000.


LINKS

Table of n, a(n) for n=1..94.
Eric Weisstein's World of Mathematics, Composite Number."


FORMULA

n appears A002808(n) times.


MATHEMATICA

Module[{nn=20, comps, len}, comps=Select[Range[nn], CompositeQ]; len=Length[ comps]; Flatten[Table[#[[1]], {#[[2]]}]&/@Thread[{Range[len], comps}]]] (* Harvey P. Dale, Aug 17 2014 *)


CROSSREFS

Cf. A002808, A111653, A111655.
Sequence in context: A259361 A111854 A132085 * A264749 A240567 A067099
Adjacent sequences: A111651 A111652 A111653 * A111655 A111656 A111657


KEYWORD

easy,nonn


AUTHOR

Jonathan Vos Post, Aug 12 2005


STATUS

approved



