A104822 - OEIS

%I #9 Mar 27 2015 23:02:14

%S 31,41,59,53,89,97,79,23,43,83,79,2,41,19,97,71,37,5,97,59,23,7,89,3,

%T 53,11,17,67,79,13,23,47,5,23,31,17,53,59,11,11,17,2,41,2,19,11,5,59,

%U 29,89,3,19,97,59,61,47,23,37,67,83,31,71,19,23,3,61,43,13,7,2,41,73,37,31,17

%N 2-digit prime numbers from decimal expansion of Pi.

%C Start with decimal expansion of Pi, 3,1,4,1,5,9,2,6,5,3,5,8,9,7,9,3,2,3,8,4,6,2,6,4,3... Make the sections with two successive digits: s={3,1},{1,4},{4,1},{1,5},{5,9},{9,2},{2,6},{6,5},{5,3},{3,5},{5,8},{8,9},{9,7},{7,9},{9,3},{3,2},{2,3},... Then A104822(n) = prime number from digits of [s(m)]: 31,41,59,53,89,97,79,23,...

%C Note that leading zeros are allowed, so the sequence of digits ...02...05...07...03... leads to the terms a(12)=2, a(18)=5, a(22)=7, a(24)=3, etc. - _M. F. Hasler_, Oct 25 2011

%t Select[ FromDigits /@ Partition[ RealDigits[Pi, 10, 330][[1]], 2, 1], PrimeQ[ # ] &] (* _Robert G. Wilson v_, Mar 28 2005 *)

%o (PARI) for(i=1,99,isprime(p=Pi\.1^i%100)&print1(p","))  \\ _M. F. Hasler_, Oct 25 2011

%K nonn,base

%O 1,1

%A _Zak Seidov_, Mar 27 2005

%E More terms from _Robert G. Wilson v_, Mar 28 2005