Number of lucky 4,6 triples <= 10^n.A055727Number of lucky 4,6 triples <= 10^n.Terms a(0) =0a(1) =2a(2) =4a(3) =14a(4) =51a(5) =247a(6) =1405a(7) =8506a(8) =55228External referencesoeis: A055727