OFFSET
1,2
COMMENTS
For n > 1, numbers n such that the n-th composite number is odd. - Charles R Greathouse IV, Apr 03 2012
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
FORMULA
a(n) ~ 2n since the primes have density 0. Charles R Greathouse IV, Apr 03 2012
EXAMPLE
8 is in the sequence since prime(8)=19, composite(8)=15, and their average 17 is an integer.
MATHEMATICA
c[x_] := FixedPoint[x+PrimePi[ # ]+1&, x] Do[s=(Prime[n]+c[n])/2; If[IntegerQ[s], Print[s]], {n, 1, 256}]
PROG
(PARI) print1(n=1); for(c=6, 1e3, if(isprime(c), next); n++; if(c%2, print1(", "n))) \\ Charles R Greathouse IV, Apr 03 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Labos Elemer, Jul 31 2002
STATUS
approved