query: PREFIX wd: <http://www.wikidata.org/entity/>
  PREFIX wdt: <http://www.wikidata.org/prop/direct/>
  PREFIX wikibase: <http://wikiba.se/ontology#>
  PREFIX gas: <http://www.bigdata.com/rdf/gas#>
  
  SELECT (?depth/2 as ?number) (count(?actor) as ?cnt) {
    SERVICE gas:service {
       gas:program gas:gasClass "com.bigdata.rdf.graph.analytics.BFS" ;
       gas:in wd:Q106418 ; gas:out ?actor ; gas:out1 ?depth ; gas:linkType wdt:P161 ; gas:traversalDirection "Undirected" .
    }
    FILTER( ?depth < 23 && ?depth/2 = xsd:integer(?depth/2)) .
  } 
  group by ?depth
  order by ?number
  