cp's OEIS Frontend

A088640 Smallest number suffixed to concatenation of n times n gives a prime.

%I A088640 #8 Feb 11 2021 19:24:20
%S A088640 2,1,3,1,9,7,29,1,3,7,39,1,23,1,97,1,91,37,59,9,93,19,97,61,293,61,3,
%T A088640 1,57,7,43,61,7,53,31,127,353,67,841,187,9,3,179,429,127,97,3,319,11,
%U A088640 51,39,191,33,3,41,7,39,47,73,81,401,57,441,571,957,997,1,19,291,173,9,417
%N A088640 Smallest number suffixed to concatenation of n times n gives a prime.
%e A088640 a(6) = 29 and 66666629 is prime.
%p A088640 a:= proc(n) local d, h, s;
%p A088640       s:= parse(cat(0, n$n));
%p A088640       for d from 0 do
%p A088640         for h to 10^d-1 do
%p A088640           if isprime(s+h) then return h fi
%p A088640         od:
%p A088640         s:= s*10;
%p A088640       od
%p A088640     end:
%p A088640 seq(a(n), n=0..75);  # _Alois P. Heinz_, Feb 11 2021
%Y A088640 Cf. A088639.
%K A088640 base,nonn
%O A088640 0,1
%A A088640 _Amarnath Murthy_, Oct 27 2003
%E A088640 More terms from _Ray Chandler_, Nov 01 2003
%E A088640 a(0)=2 prepended by _Alois P. Heinz_, Feb 11 2021