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 A144570 Nonprime(prime(n)). 4
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 OFFSET 1,2 COMMENTS The nonprimes A141468 at prime indices. [From Juri-Stepan Gerasimov, Jul 22 2011] LINKS FORMULA a(n)=A141468(A000040(n)). EXAMPLE If n=1, then a(1)=nonprime(prime(1))=nonprime(2)=1. If n=2, then a(2)=nonprime(prime(2))=nonprime( 3)=4. If n=3, then a(3)=nonprime(prime(3))=nonprime(5)=8, etc. MAPLE A141468 := proc(n) option remember ; if n <= 2 then n-1 ; else for a from procname(n-1)+1 do if not isprime(a) then return a; end if; end do: end if; end proc: A144570 := proc(n) A141468(ithprime(n)) ; end proc: seq(A144570(n), n=1..100) ; [From R. J. Mathar, Mar 18 2010] CROSSREFS Cf. A000040, A141468. Sequence in context: A153975 A020169 A082934 * A036311 A020209 A046559 Adjacent sequences:  A144567 A144568 A144569 * A144571 A144572 A144573 KEYWORD nonn AUTHOR Juri-Stepan Gerasimov, Jan 07 2009 STATUS approved

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