A082463 Numbers k such that A072181(k) + 1 is prime.

1, 2, 3, 4, 5, 6, 7, 9, 10

Offset: 1

Author

Naohiro Nomoto, Apr 26 2003

Keywords

• hard
• more
• nonn

Comments

a(10), if it exists, is greater than 47; any corresponding primes would have more than 40,000 decimal digits. - Charles R Greathouse IV, Oct 16 2015

a(10), if it exists, is greater than 66. - Michael S. Branicky, Dec 23 2024

Crossrefs

Cf. A072181, A082464.

Programs

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~))
for(n=1,1e4,k=stepA072181(k,n); if(ispseudoprime(k+1),print1(n", "))) \\ Charles R Greathouse IV, Oct 16 2015