Triangular numbers composed of digits {1,4,6}.

Terms

a(0) =1a(1) =6a(2) =66a(3) =666a(4) =6441a(5) =41616a(6) =146611a(7) =464166a(8) =1464616a(9) =4114146a(10) =14116641a(11) =664611111a(12) =1164441411a(13) =16646464416a(14) =41641661166a(15) =66114661161a(16) =144161141446a(17) =161646441166