Numbers k such that k and k^2 use only the digits 1, 2, 3, 6 and 7.

Terms

a(0) =1a(1) =6a(2) =11a(3) =26a(4) =61a(5) =111a(6) =131a(7) =276a(8) =611a(9) =2761a(10) =11731a(11) =12776a(12) =27611a(13) =36361a(14) =36376a(15) =37111a(16) =116731a(17) =116761a(18) =161761a(19) =163131a(20) =611361a(21) =613361a(22) =1166731a(23) =1166761a(24) =1171376a(25) =1273276a(26) =1277761a(27) =1327261a(28) =1616376a(29) =1636361