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 A306107 #7 Oct 06 2018 09:37:58
%S A306107 0,1,2,3,4,10,20,21,30,31,32,40,41,42,43,101,102,103,104,201,202,203,
%T A306107 204,212,213,214,301,302,303,304,312,313,314,323,324,401,402,403,404,
%U A306107 412,413,414,423,424,434,1010,1020,1021,1030,1031,1032,1040,1041,1042,1043,2010,2020,2021,2030,2031,2032,2040,2041
%N A306107 Numbers with digits in {0,1,2,3,4} such that every other digit is strictly less than its neighbors.
%C A306107 Terms of A032860 written in base 5.
%F A306107 a(n) = A007091(A032860(n)).
%o A306107 (PARI) A(Nmax=100, K=4, A=[0..K], i=vector(2*K, i, max(1, i-K+1)), c(T, v)=apply(t->t+T, v))={for(n=0, oo, for(k=10, K*11, if(k%10<k\10, k%10|| i=concat(i, 1+#A))&& A=concat(A, c(k*10^n, A[i[K*n+k%10+1]..i[K*n+K+1]-1])); #A<Nmax||return(A)))}
%Y A306107 Cf. A306105 .. A306111 and A297147: analog for bases 3..9 and 10.
%Y A306107 Cf. A032860 and A032858 .. A032865 for other bases 3..10.
%K A306107 nonn,base
%O A306107 1,3
%A A306107 _M. F. Hasler_, Oct 05 2018