This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A089394 #13 Aug 13 2017 21:39:47
%S A089394 7,89,881,8821,80849,864883,8608081,48804809,608844043,0,0,0,0,0,0,0
%N A089394 Largest n-digit member of A089392, or 0 if there is no such n-digit term.
%C A089394 A089392 has no members with 10, 11, or 12 digits. It is unlikely that it has any with more than 12 digits. - _David Wasserman_, Sep 15 2005
%C A089394 _Giovanni Resta_ has checked this up to 16 digits. Indeed 5391391551358 and 97393713331910 are the only 13- resp. 14-digit numbers (not primes) with this property, i.e., in A252996. See _Carlos Rivera_'s puzzle page for a probabilistic argument concerning the finiteness. - _M. F. Hasler_, Dec 25 and Dec 28 2014
%H A089394 C. Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_401.htm">Puzzle 401. Magnanimous primes</a>, 2007.
%p A089394 with(combinat): ds:=proc(s) local j: RETURN(add(s[j]*10^(j-1),j=1..nops(s))):end: for d from 1 to 6 do sch:=[seq([1,op(i),d+1],i=[[],seq([j],j=2..d)])]: for n from 10^d-1 by -1 to 10^(d-1) do sn:=convert(n,base,10): fl:=0: for s in sch do m:=add(j,j=[seq(ds(sn[s[i]..s[i+1]-1]),i=1..nops(s)-1)]): if not isprime(m) then fl:=1: break fi od: if fl=0 then printf("%d, ",n):break fi od od: # C. Ronaldo
%Y A089394 Cf. A089392, A089393, A252996, A252495.
%K A089394 base,nonn
%O A089394 1,1
%A A089394 _Amarnath Murthy_, Nov 10 2003
%E A089394 More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 25 2004
%E A089394 3 more terms from _David Wasserman_, Sep 15 2005
%E A089394 Definition edited and a(10..16) = 0 added by _M. F. Hasler_, Dec 28 2014