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 A284806 #6 Apr 05 2017 05:37:30 %S A284806 3,12,18,24,30,36,42,75,123,171,219,267,315,390,432,474,516,558,600, %T A284806 642,732,774,816,858,900,942,984,1074,1116,1158,1200,1242,1284,1326, %U A284806 1416,1458,1500,1542,1584,1626,1668,1758,1800,1842,1884,1926,1968,2010,2100,2142 %N A284806 Fixed points of the transform A284805. %e A284806 219 is a term of the sequence because 219 in base 7 is 432, its complement in base 7 is 234 and the digit reverse is again 432 that is 219 in base 10. %p A284806 P:=proc(q,h) local a,b,k,n; for n from 1 to q do a:=convert(n,base,h); b:=0; %p A284806 for k from 1 to nops(a) do a[k]:=h-1-a[k]; b:=h*b+a[k]; od; if b=n then print(n); fi; od; end: P(10^2,7); %Y A284806 Cf. A035928, A284805. %K A284806 nonn,base,easy %O A284806 1,1 %A A284806 _Paolo P. Lava_, Apr 03 2017