# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a119043 Showing 1-1 of 1 %I A119043 #13 Mar 31 2023 13:21:15 %S A119043 1,10,171,1711,1770,10011,111117701071,17170010070077710, %T A119043 101711101707777771,701000700077010700,1701111717707771071, %U A119043 10010107100007777700,101770070070071771070,170107111111710707070,1177170070777107111711,70071707101001717077017171 %N A119043 Triangular numbers composed of digits {0,1,7}. %H A119043 Giovanni Resta, Tridigital Triangular Numbers. %F A119043 a(n) = A000217(A119044(n)). - _Tyler Busby_, Mar 31 2023 %t A119043 Select[FromDigits/@Tuples[{0,1,7},12],OddQ[Sqrt[8#+1]]&] (* The program generates the first 8 terms of the sequence. *) (* _Harvey P. Dale_, Sep 06 2022 *) %Y A119043 Cf. A000217, A058420, A119044. See A119033 for a table of cross-references. %K A119043 nonn,base %O A119043 1,2 %A A119043 _Giovanni Resta_, May 10 2006 %E A119043 a(15)-a(16) from _Tyler Busby_, Mar 22 2023 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE