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 A256421 Odd numbers and twice primes, sorted. 2

%I

%S 1,3,4,5,6,7,9,10,11,13,14,15,17,19,21,22,23,25,26,27,29,31,33,34,35,

%T 37,38,39,41,43,45,46,47,49,51,53,55,57,58,59,61,62,63,65,67,69,71,73,

%U 74,75,77,79,81,82,83,85,86,87,89,91,93,94

%N Odd numbers and twice primes, sorted.

%H Charles R Greathouse IV, <a href="/A256421/b256421.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) ~ 2n. - _Charles R Greathouse IV_, Apr 07 2015

%t Select[Range@94,PrimeQ[#/2]||OddQ[#]&] (* _Ivan N. Ianakiev_, Apr 08 2015 *)

%o (PARI) lista(nn) = nb = primepi(nn)\2; vecsort(setunion(vector(prime(nb), n, 2*n-1), 2*primes(nb))); \\ _Michel Marcus_, Apr 07 2015

%o (PARI) list(lim)=setunion(vector((lim+1)\2,i,2*i-1), 2*primes([2,lim])) \\ _Charles R Greathouse IV_, Apr 07 2015

%Y Cf. A256420.

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Apr 07 2015

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Last modified September 19 07:08 EDT 2021. Contains 347554 sequences. (Running on oeis4.)