A089018 Smallest prime dividing the composite number consisting of A089017(n) successive 3's followed by a terminal 1.

17, 673, 307, 19, 523, 607, 181, 199, 31, 1009, 29, 23, 177943, 61, 312929, 17, 821, 353, 363941, 829, 19, 686269, 31, 1019, 2761379, 145501, 1397023, 28529353, 47, 2543, 17, 439, 23, 59, 70717063, 15683, 31, 19, 4555681103, 10616546557, 28759, 83

Offset: 1

Author

Lekraj Beedassy, Nov 04 2003

Keywords

• base
• nonn

Links

• Factordb, (10^n-7)/3
• Makoto Kamada, Factorizations of 33...331

Programs

PARI

do(lim)=my(v=List());for(n=9,lim+1,if(ispseudoprime(10^n\3-2), next); forprime(p=7,,if(Mod(10,p)^n==7,listput(v,p); next(2)))); Vec(v) \\ tests numbers with A089017(n) <= m; Charles R Greathouse IV, Oct 23 2013

Extensions

More terms from Ray Chandler, Nov 04 2003