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.
SequencePosition[Table[If[SequenceCount[IntegerDigits[n,8],{2,5}]>0 || SequenceCount[ IntegerDigits[ n,8],{5,2}]>0,1,0],{n,1500}],{0,1}][[;;,2]] (* Harvey P. Dale, Jun 02 2024 *)
Select[Range[300],DigitCount[#,8,0]==1&] (* Harvey P. Dale, Jul 15 2014 *)
g:= proc(x) local j; seq(8*x+j,j=1..7) end proc:
h:= x -> 8*x:
B[1,0]:= {$1..7}:
for d from 2 to 5 do
B[d,0]:= map(g, B[d-1,0]);
for i from 1 to min(d-2,3) do
B[d,i]:= map(g, B[d-1,i]) union map(h, B[d-1,i-1])
od;
if d <= 4 then B[d,d-1]:= map(h, B[d-1,d-2]) fi;
od:
sort(convert(B[4,3] union B[5,3], list)); # Robert Israel, Jan 15 2019
Select[Range[10000],DigitCount[#,8,0]==3&] (* Harvey P. Dale, Nov 25 2018 *)
Select[Range[600],DigitCount[#,8,1]==2&] (* Harvey P. Dale, Feb 26 2020 *)
F:= proc(d) local r, L,M,S, Res; # to get all terms < 8^d
Res:= NULL;
for S in combinat:-choose(d,d-4) do
L:= Vector(d,2);
for r from 0 to 7^(d-4)-1 do
M:= subs(2=7,convert(r+7^(d-4),base,7)[1..d-4]);
L[S]:= Vector(M);
Res:= Res, add(8^(i-1)*L[i],i=1..d);
od
od;
sort([Res]);
end proc:
F(6); # Robert Israel, Mar 20 2018
Select[Range[0, 30000], DigitCount[#, 8, 2]==4 &] (* Vincenzo Librandi, Mar 21 2018 *)
isok(n) = #select(x->(x==2), digits(n, 8)) == 4; \\ Michel Marcus, Mar 21 2018
filter:= proc(n) numboccur(6,convert(n,base,8)) = 1 end proc: select(filter, [$1..1000]); # Robert Israel, Nov 27 2024
Select[Range[500], DigitCount[#, 8, 6] == 1 &] (* Paolo Xausa, Nov 26 2024 *)
Select[Range[1300],DigitCount[#,8,6]==2&] (* Harvey P. Dale, May 16 2012 *)
filter:= proc(n) numboccur(6, convert(n, base, 8)) = 3 end proc:select(filter, [$1..10000]); # Robert Israel, Nov 27 2024
G:= proc(x,c,d) local L,m1,m2;
L:= convert(x,base,7);
m2:= nops(c);
m1:= min(nops(L),m2);
8^d-1 + add((L[i]-7)*8^(c[i]-1),i=1..m1) - 7*add(8^(c[i]-1),i = m1+1..m2)
end proc:
sort([seq(seq(G(x,c,6), x = 0 .. 7^2-1), c=combinat:-choose(6,2))]); # Robert Israel, Sep 24 2017
Select[Range[0, 10^5], DigitCount[#, 8, 7]==4 &] (* Vincenzo Librandi, Sep 25 2017 *)
isok(n) = #select(x->(x==7), digits(n, 8)) == 4; \\ Michel Marcus, Sep 25 2017