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.
f:= proc(n) local q, q2, q5, n1, R, Agenda,d, newA, t, t1, t2;
q2:= padic:-ordp(n,2);
q5:= padic:-ordp(n,5);
q:= max(q2,q5);
n1:= n/2^q2/5^q5;
R[7]:= 7: Agenda:= {7}:
if 7 mod n1 = 0 then return 10^q*7/n fi;
for d from 2 do
newA:= NULL;
for t in Agenda do
t1:= 10*t mod n1;
if not assigned(R[t1]) then
R[t1]:= 10*R[t];
newA:= newA, t1;
fi;
t2:= (10*t+7) mod n1;
if t2 = 0 then
return 10^q*(10*R[t]+7)/n;
break
elif not assigned(R[t2]) then
R[t2]:= 10*R[t]+7;
newA:= newA,t2;
fi;
od;
Agenda:= [newA];
od:
end proc:
map(f, [$1..50]); # Robert Israel, Mar 06 2017
f07[n_]:=Module[{k=1},While[!SubsetQ[{0,7},IntegerDigits[n*k]],k++];k]; Array[f07,8] (* The program generates the first 8 terms of the sequence. To generate more, increase the Array constant but because some of the terms are quite large the program may take a long time to run. *) (* Harvey P. Dale, Sep 25 2024 *)
def A096687(n): if n > 0: for i in range(1, 2**n): q, r = divmod(8*int(bin(i)[2:]), n) if not r: return q return 1 # Chai Wah Wu, Jan 02 2015
Array[Which[GCD[#, 10] != 1, -1, Mod[#, 3] == 0, Block[{k = 1}, While[Mod[k, #] != 0, k = 10 k + 1]; k], True, (10^MultiplicativeOrder[10, #] - 1)/9] &, 42] (* Michael De Vlieger, Dec 11 2020 *)
def A216479(n): if n % 2 == 0 or n % 5 == 0: return -1 rem = 1 while rem % n != 0: rem = rem*10 + 1 return rem # Azanul Haque, Nov 28 2020
a(39) = 663 because it is the least multiple of 39 appearing in A009996.
a[n_] := Block[{x=n}, While[0 < Max@Differences@IntegerDigits@x, x += n]; x]; Array[a, 85] (* Giovanni Resta, Mar 26 2013 *)
sub A223474 { my $n = shift; my $a = $n; while ($a !~ /^9*8*7*6*5*4*3*2*1*0*$/) { $a += $n; } return $a; } foreach (1..100) { print A223474($_), ","; }
For n = 7, 15873*7 = 111111 and this is the least positive multiple of 7 that is either a repunit or of the form 1111...000.
f[n_] := Block[{id = {0, 4}, k = 1}, While[ Union[ Join[id, IntegerDigits[k*n]]] != id, k++]; k]; Array[f, 100] (* or *)
id = {0, 7}; lst = Union[ FromDigits /@ Flatten[ Table[ Tuples[id, j], {j, 15}], 1]]; If[ lst[[1]] == 0, lst = Rest@ lst]; f[n_] := (Min[ Select[lst, Mod[#, n] == 0 &]]/n) /. Infinity -> 0; Array[f, 100] (* or *)
id = {0, 7}; lst = Union[ FromDigits /@ Flatten[ Table[ Tuples[id, j], {j, 15}], 1]]; If[ lst[[1]] == 0, lst = Rest@ lst]; f[n_] := (SelectFirst[lst, Mod[#, n] == 0 &, 0]/n); a = Array[f, 100] (* requires Mathematica v10 *) (* Robert G. Wilson v, Sep 26 2016 *)
k06[n_]:=Module[{k=1},While[Max[Drop[DigitCount[k*n],{6,10,4}]]>0,k++]; k]; Array[k06,52] (* Harvey P. Dale, Dec 29 2013 *)
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