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A111654 n appears n-th 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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

REFERENCES

T. M. Apostol, Introduction to Analytic Number Theory, Springer-Verlag, 1976, page 2.

J. B. Rosser and L. Schoenfeld, Approximate formulas for some functions of prime numbers, Illinois J. Math. 6: 64-94 (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

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Last modified January 18 17:18 EST 2022. Contains 350455 sequences. (Running on oeis4.)