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A144570
Nonprime(prime(n)).
4
1, 4, 8, 10, 16, 20, 25, 27, 33, 40, 44, 51, 56, 58, 64, 72, 80, 82, 90, 94, 96, 105, 111, 118, 126, 132, 134, 140, 142, 146, 164, 169, 176, 178, 190, 194, 202, 208, 213, 219, 226, 230, 243, 245, 249, 252, 266, 282, 287, 289, 294, 300, 302, 315, 322, 328, 335
OFFSET
1,2
COMMENTS
The nonprimes A141468 at prime indices. - Juri-Stepan Gerasimov, Jul 22 2011
FORMULA
a(n) = A141468(A000040(n)).
EXAMPLE
a(1) = nonprime(prime(1)) = nonprime(2) = 1,
a(2) = nonprime(prime(2)) = nonprime(3) = 4,
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) ; # R. J. Mathar, Mar 18 2010
PROG
(PARI) c(n) = {for(k=0, primepi(n), isprime(n++)&&k--); n};
t(n) = if(n<3, n-1, c(n-2));
vector(100, n, t(prime(n))) \\ Altug Alkan, Oct 17 2015
CROSSREFS
Sequence in context: A082934 A311003 A311004 * A036311 A020209 A311005
KEYWORD
nonn
AUTHOR
STATUS
approved