Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #32 May 21 2013 08:08:58
%S 92673,143713,3579553,4110529,28688897,127017857,141127681,157648097,
%T 162101441
%N Composite numbers n such that A179382((n+1)/2)=(n-1)/(2^c) for some c > 0.
%C a(10) > 180*10^6. All terms up to a(9) are of the form 32*k+1 and except a(1) are also semiprimes. The numbers 212999489, 393300097 and 663414881 are also terms. - _Giovanni Resta_, May 21 2013
%e 143713=137*1049: A179382((143713+1)/2)=4491=(143713-1)/(2^5)
%o (PARI) oddres(n)=n>>valuation(n, 2)
%o cyc(d)=my(k=1, t=1); while((t=oddres(t+d))>1, k++); k
%o p=5;forprime(q=7,1e7,forstep(n=p+2, q-2, 2, my(t=(n-1)/cyc(n), c=valuation(t,2)); if(t>>c==1 && c>0, print1(n", ")));p=q) \\ _Charles R Greathouse IV_, May 20 2013
%Y Cf. A179382.
%K nonn,more
%O 1,1
%A _Lear Young_ and Peter Košinár, May 20 2013
%E Missing a(3) from _Giovanni Resta_, May 20 2013
%E a(6)-a(9) from _Giovanni Resta_, May 21 2013