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 A097636 Odd composites of the form A024675(k) or 1+A024675(k), any k. 0

%I

%S 9,15,21,27,35,39,45,51,57,65,69,77,81,87,93,99,105,111,121,129,135,

%T 145,155,161,165,171,177,187,195,205,217,225,231,237,247,255,261,267,

%U 275,279,289,301,309,315,325,335,343,351,357,363,371,377,381,387,393,399

%N Odd composites of the form A024675(k) or 1+A024675(k), any k.

%C Start from an auxiliary sequence of interprimes, incremented by 1 if even: 5, 7, 9, 13, 15, 19, 21, 27, 31,... Removing the primes from this auxiliary sequence of odd numbers yields the current sequence.

%t digits=200 (* find odd numbers between the primes nearest the average*) a=Table[If[(Mod[(Prime[n+1]+Prime[n])/2, 2]==1)&&( PrimeQ[(Prime[n+1]+Prime[n])/2]==False)&&( PrimeQ[(Prime[n+1]+Prime[n])/2+1]==False), (Prime[n+1]+Prime[n])/2, (Prime[n+1]+Prime[n])/2+1], {n, 2, digits}] b=Table[Prime[n], {n, 1, digits}] (* eliminate the primes from the sequence *) aa=Complement[a, b]

%K nonn,easy,less

%O 1,1

%A _Roger L. Bagula_, Sep 20 2004

%E Definition clarified by the Assoc. Eds. of the OEIS, Jul 13 2010

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Last modified September 27 21:12 EDT 2021. Contains 347698 sequences. (Running on oeis4.)