This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A321997 #5 Nov 24 2018 01:23:27 %S A321997 38,66,67,68,73,74,75,76,79,80,81,87,88,108,109,115,116,117,118,121, %T A321997 122,123,124,125,127,128,129,130,131,132,134,135,136,137,138,142,143, %U A321997 151,152,156,157,158,159,160,162,163,164,165,166,167,169,170,173,174,176,177,178,179 %N A321997 Numbers that cannot be written using seven 7's and operations +, -, * and/or /. Complement of A258068. %C A321997 A258068 contains most nonnegative integers below 115, which motivates listing the complement, even though A258068 is finite and its complement, this sequence, contains all integers above 134456 except for 235298 and 823543. (These are the last three terms of A258068.) %Y A321997 Cf. A258068 (complement), A171826, A171827, A171828, A171829, A258069, A258070, A258071 (analog for 3, ..., 10). %Y A321997 Cf. A182002, A258097. %K A321997 nonn %O A321997 1,1 %A A321997 _M. F. Hasler_, Nov 23 2018