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 A089393 #15 Aug 13 2017 21:39:20
%S A089393 2,11,101,2221,20261,220021,2000221,20266681,228440489,0,0,0,0,0,0,0
%N A089393 Smallest n-digit magnanimous prime (A089392), or 0 if there is no such prime with n digits.
%C A089393 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 A089393 _Giovanni Resta_ has checked this up to 16 digits, see _Carlos Rivera_'s puzzle page for a probabilistic argument. - _M. F. Hasler_, Dec 28 2014
%H A089393 C. Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_401.htm">Puzzle 401. Magnanimous primes</a>, 2007.
%p A089393 with(combinat): ds:=proc(s) local j: RETURN(add(s[j]*10^(j-1),j=1..nops(s))):end: for d from 1 to 10 do sch:=[seq([1,op(i),d+1],i=[[],seq([j],j=2..d)])]: for n from 10^(d-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 A089393 Cf. A089392, A089394, A252996, A252495.
%K A089393 nonn,base
%O A089393 1,1
%A A089393 _Amarnath Murthy_, Nov 10 2003
%E A089393 a(5) and a(6) from Mark Hudson (mrmarkhudson(AT)hotmail.com), Dec 15 2004
%E A089393 Corrected and extended by C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 25 2004
%E A089393 Two more terms from _David Wasserman_, Sep 15 2005
%E A089393 Definition edited and a(10..16) = 0 added by _M. F. Hasler_, Dec 28 2014