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 A121977 #8 Dec 03 2013 09:29:21 %S A121977 100000000011111112222222333333444445555666778, %T A121977 100000000011111112222222333333444445555666779, %U A121977 100000000011111112222222333333444445555666787,100000000011111112222222333333444445555666788,100000000011111112222222333333444445555666797,100000000011111112222222333333444445555666799,100000000011111112222222333333444445555666877,100000000011111112222222333333444445555666878 %N A121977 Numbers with a distinct frequency for each decimal digit. %e A121977 100000000011111112222222333333444445555666778 has 9 0's, 8 1's, 7 2's, 6 3's, 5 4's, 4 5's, 3 6's, 2 7's, 1 8 and 0 9's. 121 is not in the sequence because there are eight digits it has zero of. %Y A121977 Cf. A044959, A044951. %Y A121977 Subsequence of A179239. %K A121977 base,nonn %O A121977 1,1 %A A121977 _Franklin T. Adams-Watters_, Sep 05 2006