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%I #6 Oct 16 2015 16:30:48
%S 1,2,3,4,5,6,7,9,10
%N Numbers n such that A072181(n) + 1 is prime.
%C a(10), if it exist, is greater than 47; any corresponding primes would have more than 40,000 decimal digits. - _Charles R Greathouse IV_, Oct 16 2015
%o (PARI) stepA072181(k,n)=if(n<3, return(n)); my(f=factor(k), g=factor(n), p=Set(concat(f[,1],g[,1])), x=((f,p) -> my(i=setsearch(f[,1]~,p)); if(i,f[i,2],1)), e=apply(q->x(f,q)*x(g,q),p)); factorback(concat(Mat(p~),e~))
%o for(n=1,1e4,k=stepA072181(k,n); if(ispseudoprime(k+1),print1(n", "))) \\ _Charles R Greathouse IV_, Oct 16 2015
%K hard,more,nonn
%O 1,2
%A _Naohiro Nomoto_, Apr 26 2003
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