A198019 Primes occurring in the decimal expansion of Pi (A000796), ordered by position of last digit, then by size.
3, 31, 41, 5, 59, 4159, 14159, 314159, 2, 53, 653, 1592653, 89, 141592653589, 7, 97, 5897, 35897, 6535897, 5926535897, 415926535897, 79, 58979, 358979, 589793, 23, 9323, 9265358979323, 43, 643, 462643, 93238462643, 433, 83, 383, 2643383, 38462643383, 89793238462643383, 41592653589793238462643383
Offset: 1
Examples
In Pi = 3... we have the prime a(1)=3. In Pi = 3.1.... we have the prime a(2)=31. In Pi = 3.14... we have no new prime. In Pi = 3.141.... we have the prime a(3)=41. In Pi = 3.1415.... we have the new prime a(5)=5. In Pi = 3.14159.... we have the new primes (listed in increasing order) a(6)=59, a(7)=4159, a(8)=14159 and a(9)=314159. [_M. F. Hasler_, Sep 01 2013]
Programs
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PARI
{t=Pi; u=[]; for(i=0,precision(t), for(k=1,i+1, ispseudoprime(p=t\.1^i%10^k)& !setsearch(u,p)& (u=setunion(u,Set(p)))&print1(p",")))}
Comments