cp's OEIS Frontend

A022449 c(p(n)) where p(k) is k-th prime including p(1)=1 and c(k) is k-th composite number.

%I A022449 #23 Jan 26 2018 05:19:30
%S A022449 4,6,8,10,14,20,22,27,30,35,44,46,54,58,62,66,75,82,85,92,96,99,108,
%T A022449 114,120,129,134,136,142,144,148,166,171,178,182,194,196,204,210,215,
%U A022449 221,230,232,245,247,252,254,268,285,289,291,296,302,304,318
%N A022449 c(p(n)) where p(k) is k-th prime including p(1)=1 and c(k) is k-th composite number.
%C A022449 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]
%D A022449 C. Kimberling, Fractal sequences and interspersions, Ars Combinatoria, vol. 45 p 157 1997.
%H A022449 Reinhard Zumkeller, <a href="/A022449/b022449.txt">Table of n, a(n) for n = 1..10000</a>
%H A022449 C. Kimberling, <a href="http://faculty.evansville.edu/ck6/integer/intersp.html">Interspersions</a>
%F A022449 a(n) = A002808(A008578(n)). - _Jaroslav Krizek_, Mar 13 2010
%e A022449 a(5) = 14 because a(5) = composite(noncomposite(5)) = composite(7) =14. _Jaroslav Krizek_, Mar 13 2010
%p A022449 A022449 := proc(n)
%p A022449     A002808(A008578(n)) ;
%p A022449 end proc:
%p A022449 seq(A022449(n),n=1..40) ; # _R. J. Mathar_, Jan 28 2014
%t A022449 p[1] = 1; p[n_] := Prime[n - 1];
%t A022449 Composite[n_] := FixedPoint[n + PrimePi[#] + 1 & , n + PrimePi[n] + 1];
%t A022449 a[n_] := Composite[p[n]];
%t A022449 Array[a, 100] (* _Jean-François Alcover_, Jan 26 2018, after _Robert G. Wilson v_ *)
%o A022449 (Haskell)
%o A022449 a022449 = a002808 . a008578
%o A022449 a022449_list = map a002808 a008578_list
%o A022449 -- _Reinhard Zumkeller_, Jan 12 2013
%Y A022449 A065858 with a leading 4.
%K A022449 nonn
%O A022449 1,1
%A A022449 _Clark Kimberling_
%E A022449 Definition corrected by Christopher M. Tomaszewski (cmt1288(AT)comcast.net), Mar 30 2005