var limit  = 1e6
var primes = limit.primes

say "Groups of successive primes <= #{limit.commify}:"

for diffs in [[2], [1], [2,2], [2,4], [4,2], [6,4,2]] {

    var groups = []
    primes.each_cons(diffs.len+1, {|*group|
        if (group.map_cons(2, {|a,b| b-a}) == diffs) {
            groups << group
        }
    })

    say ("...for differences #{diffs}, there are #{groups.len} groups, where ",
         "the first group = #{groups.first} and the last group = #{groups.last}")
}