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A022449 c(p(n)) where p(k) is k-th prime including p(1)=1 and c(k) is k-th composite number. 9
4, 6, 8, 10, 14, 20, 22, 27, 30, 35, 44, 46, 54, 58, 62, 66, 75, 82, 85, 92, 96, 99, 108, 114, 120, 129, 134, 136, 142, 144, 148, 166, 171, 178, 182, 194, 196, 204, 210, 215, 221, 230, 232, 245, 247, 252, 254, 268, 285, 289, 291, 296, 302, 304, 318 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) U A050435(n) = A002808(n), a(n+1) U A175251(n) = A002808(n) for n >= 1. a(n) = A065858(n-1) = composites (A002808) with prime (A000040) subscripts for n >=2. [From Jaroslav Krizek, Mar 13 2010]

REFERENCES

C. Kimberling, Fractal sequences and interspersions, Ars Combinatoria, vol. 45 p 157 1997.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

C. Kimberling, Interspersions

FORMULA

a(n) = A002808(A008578(n)). - Jaroslav Krizek, Mar 13 2010

EXAMPLE

a(5) = 14 because a(5) = composite(noncomposite(5)) = composite(7) =14. Jaroslav Krizek, Mar 13 2010

MAPLE

A022449 := proc(n)

    A002808(A008578(n)) ;

end proc:

seq(A022449(n), n=1..40) ; # R. J. Mathar, Jan 28 2014

MATHEMATICA

p[1] = 1; p[n_] := Prime[n - 1];

Composite[n_] := FixedPoint[n + PrimePi[#] + 1 & , n + PrimePi[n] + 1];

a[n_] := Composite[p[n]];

Array[a, 100] (* Jean-Fran├žois Alcover, Jan 26 2018, after Robert G. Wilson v *)

PROG

(Haskell)

a022449 = a002808 . a008578

a022449_list = map a002808 a008578_list

-- Reinhard Zumkeller, Jan 12 2013

CROSSREFS

A065858 with a leading 4.

Sequence in context: A069148 A328144 A103800 * A088686 A161344 A127792

Adjacent sequences:  A022446 A022447 A022448 * A022450 A022451 A022452

KEYWORD

nonn

AUTHOR

Clark Kimberling

EXTENSIONS

Definition corrected by Christopher M. Tomaszewski (cmt1288(AT)comcast.net), Mar 30 2005

STATUS

approved

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Last modified December 15 20:00 EST 2019. Contains 330000 sequences. (Running on oeis4.)