A127890 - OEIS

%I #18 Aug 25 2020 22:21:45

%S 7,79,797,7393,73939,739399,7393933,73939133

%N Largest n-digit right-truncatable prime.

%C For a variant see the Howard reference. - _Alexander R. Povolotsky_, Dec 23 2007

%C Right-truncatable means that the integer part of successive divisions by 10 always yields primes (or zero). - _M. F. Hasler_, Nov 07 2018

%D Toby Howard, "Magic Pi - The Magic of Numbers", PC Advisor magazine, May 1998.

%H I. O. Angell and H. J. Godwin, <a href="http://dx.doi.org/10.1090/S0025-5718-1977-0427213-2">On Truncatable Primes</a>, Math. Comput. 31, 265-267, 1977.

%H Jens Fehlau, <a href="https://www.youtube.com/watch?v=5BFDdVqAFZE">73939133 - Probably the Most Interesting Prime Number [Part 1]</a> and <a href="https://www.youtube.com/watch?v=f2lEB4nMmyI">[Part 2]</a>, Flammable Maths videos (2020).

%H <a href="/index/Tri#tprime">Index entries for sequences related to truncatable primes</a>

%o (PARI) A127890=vector(8, n, p=concat(apply(t->primes([t, t+1]*10), if(n>1, p)));p[#p]) \\ _M. F. Hasler_, Nov 07 2018

%Y Cf. A024770, A050986, A127889.

%K base,nonn,fini,full

%O 1,1

%A _Ray Chandler_, Feb 04 2007