find_ruby_shaped_prime.rb

def prime_test?(n, a)
  a.pow(n-1,n)==1
end

def ruby_mark(n,m,x,y)
  0.5*x.abs+y.abs<n && y>-m
end

def pattern(ow, oh, iw, ih)
  ((1-oh)..ow).map{|y|
    (-(ow*2).round..ow*2-1).map{|x|
      ruby_mark(iw,ih,x+0.5,y) ? 'a' : ruby_mark(ow,oh,x+0.5,y) ? 'b' : 'c'
    }.join
  }
end
# puts (-5..10).map{|y|(-21..20).map{|x|ruby_mark(10.5,6,x+0.5,y)!=ruby_mark(8.5,4,x+0.5,y) ? '#' : ' '}.join}
# puts (-4..8).map{|y|(-17..16).map{|x|ruby_mark(8.5,5,x+0.5,y)!=ruby_mark(6.5,3,x+0.5,y) ? '#' : ' '}.join}
# puts (-4..8).map{|y|(-17..16).map{|x|ruby_mark(8.5,5,x+0.5,y)!=ruby_mark(6.5,3,x+0.5,y) ? '#' : ' '}.join}
def generate
  [
  [8.5,5,6.5,3],
  [8.5,5,7,4],
  [8.5,5,7,3],
  [8.5,5,6,3],
  [8.5,5,5,2],
  [8.5,5,7.5,4],
  [8.5,5,0,0],
  [7.5,5,6.5,4],
  [7.5,5,6,4],
  [7.5,5,6,3],
  [7.5,5,5.5,3],
  [7.5,5,0,0],
  [7.5,4,6.5,3],
  [7.5,4,5.5,2],
  [7.5,4,5,2],
  [7.5,4,0,0],
  [6.5,4,5.5,3],
  [6.5,4,5,2],
  [6.5,4,4.5,2],
  [6.5,4,0,0]
  ].reverse_each do |ow,oh,iw,ih|
    lines = pattern(ow,oh,iw,ih)
    [[0,0],[1,1],[2,1],[2,2],[3,1],[3,2],[3,3]].each do |mx,my|
      l = ('c'*(lines[0].size+2*mx)+"\n")
      yield l*my+lines.map{'c'*mx+_1+'c'*mx+"\n"}.join+l*my
    end
  end
end

generate do |s|
  bg = 1
  (2..9).each do |max|
    nums = (2..max).to_a
    nums.size.times do |start|
      ns = s.gsub(/a|c/, bg.to_s).lines.map.with_index do |l,i|
        l.chars.map.with_index do |c, j|
          c.match?(/b/) ? nums[(start+i+j/2)%nums.size] : c
        end.join
      end.join
      n = ns.delete("\n").to_i
      next if n%2==0||n%3==0||n%5==0||n%7==0
      if prime_test?(n, 2) && prime_test?(n, 3) && prime_test?(n, 5) && prime_test?(n, 7)
        puts ns
        puts
      end
    end
  end
end

find_ruby_shaped_prime2.rb

def prime_test?(n, a)
  a.pow(n-1,n)==1
end

def generate
  pattern = <<~EOS
    1111112222222222222222222111111
    1111223333333333333333333221111
    1122334444444444444444444332211
    2233444444444444444444444443322
    1122334444444444444444444332211
    1111223344444444444444433221111
    1111112233444444444443322111111
    1111111122334444444332211111111
    1111111111223344433221111111111
    1111111111112233322111111111111
    1111111111111122211111111111111
  EOS
  lines = pattern.chomp.split("\n")
  [[0,0],[1,0],[2,0],[0,1],[0,2],[1,2],[1,1],[2,1],[2,2],[3,1],[3,2],[3,3]].each do |mx,my|
    l = ('1'*(lines[0].size+2*mx)+"\n")
    yield l*my+lines.map{'1'*mx+_1+'1'*mx+"\n"}.join+l*my
  end
end

generate do |s|
  [*2..9].product([*1..9],[*1..9]).each do |a,b,c|
    ns = s.tr('234', [a,b,c].join)
    n = ns.delete("\n").to_i
    next if n%2==0||n%3==0||n%5==0||n%7==0
    if prime_test?(n, 2) && prime_test?(n, 3) && prime_test?(n, 5) && prime_test?(n, 7)
      puts ns
      puts
    end
  end
end

prime.rb

require 'faster_prime'
n = %w(
  1111111111111111111111111111111
  1111118888888888888888888111111
  1111888888888888888888888881111
  1188881111111111111111111888811
  8888111111111111111111111118888
  1188881111111111111111111888811
  1111888811111111111111188881111
  1111118888111111111118888111111
  1111111188881111111888811111111
  1111111111888811188881111111111
  1111111111118888888111111111111
  1111111111111188811111111111111
  1111111111111111111111111111111
).join.to_i
puts "#{n}.prime? #=> #{n.prime?}"

n = %w(
  111111111111111111111111111111111111
  111111111677889922334455667111111111
  111111167788992233445566778891111111
  111116778899223344556677889922311111
  111677889922334455667788992233445111
  111118992233445566778899223344511111
  111111123344556677889922334451111111
  111111111455667788992233445111111111
  111111111116778899223344511111111111
  111111111111189922334451111111111111
  111111111111111233445111111111111111
  111111111111111114511111111111111111
  111111111111111111111111111111111111
).join.to_i
puts "#{n}.prime? #=> #{n.prime?}"