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.
a004290 0 = 0 a004290 n = head [x | x <- tail a007088_list, mod x n == 0] -- Reinhard Zumkeller, Jan 10 2012
f:= proc(n)
local L,x,m,r,k,j;
if n<2 then return n fi;
for x from 2 to n-1 do L[0,x]:= 0 od:
L[0,0]:= 1: L[0,1]:= 1;
for m from 1 do
if L[m-1,(-10^m) mod n] = 1 then break fi;
L[m,0]:= 1;
for k from 1 to n-1 do
L[m,k]:= max(L[m-1,k],L[m-1,k-10^m mod n])
od;
od;
r:= 10^m; k:= -10^m mod n;
for j from m-1 by -1 to 1 do
if L[j-1,k] = 0 then
r:= r + 10^j; k:= k - 10^j mod n;
fi
od;
if k = 1 then r:= r + 1 fi;
r
end proc:
seq(f(n),n=1..100); # Robert Israel, Feb 09 2016
a[n_] := For[k = 1, True, k++, b = FromDigits[ IntegerDigits[k, 2] ]; If[Mod[b, n] == 0, Return[b]]]; a[0] = 0; Table[a[n], {n, 0, 34}] (* Jean-François Alcover, Jun 14 2013, after Reinhard Zumkeller *)
With[{c=Rest[Union[FromDigits/@Flatten[Table[Tuples[{1,0},i],{i,10}], 1]]]}, Join[{0},Flatten[ Table[ Select[c,Divisible[#,n]&,1],{n,40}]]]] (* Harvey P. Dale, Dec 07 2013 *)
a(n) = {if( n==0, return (0)); my(m = n); while (vecmax(digits(m)) != 1, m+=n); m;} \\ Michel Marcus, Feb 09 2016, May 27 2020
apply( {A004290(n)=for(k=1,2^n,(t=fromdigits(binary(k)))%n||return(t))}, [1..44]) \\ M. F. Hasler, Mar 04 2025
def A004290(n): if n > 0: for i in range(1,2**n): x = int(bin(i)[2:]) if not x % n: return x return 0 # Chai Wah Wu, Dec 30 2014
a078241 n = head [x | x <- tail a169965_list, mod x n == 0] -- Reinhard Zumkeller, Jan 10 2012
Module[{m=Rest[FromDigits/@Tuples[{0,2},12]]},Table[Select[m,Divisible[ #,n]&,1],{n,40}]]//Flatten (* Harvey P. Dale, Jul 31 2017 *)
def A078241(n): if n > 0: for i in range(1,2**n): x = 2*int(bin(i)[2:]) if not x % n: return x return 0 # Chai Wah Wu, Dec 30 2014
a078248 n = head [x | x <- tail a097256_list, mod x n == 0] -- Reinhard Zumkeller, Jan 10 2012
With[{t=Flatten[Table[FromDigits[Join[{9},#]]&/@Tuples[{0,9},n],{n,0,6}]]},Flatten[Table[Select[t,Divisible[#,i]&,1],{i,50}]]] (* Harvey P. Dale, May 31 2014 *)
isok(n) = my(vd = vecsort(digits(n),,8)); (vd == [0,2]) || (vd == [2]); a(n) = my(k=1); while(!isok(k*n), k++); k; \\ Michel Marcus, Sep 25 2016
def next02(n):
s = str(n)
if s > '2'*len(s): return int('2' + '0'*len(s))
for i, c in enumerate(s):
if c == '1': return int(s[:i] + '2' + '0'*(len(s)-i-1))
elif s[i:] > '2'*(len(s)-i): return int(s[:i-1] + '2' + '0'*(len(s)-i))
def a(n):
k = 1
while set(str(k*n)) - set('02') != set(): k = max(k+1, next02(k*n)//n)
return k
print([a(n) for n in range(1, 51)]) # Michael S. Branicky, Feb 01 2021
a078242 n = head [x | x <- tail a169966_list, mod x n == 0] -- Reinhard Zumkeller, Jan 10 2012
With[{lst=Rest[FromDigits/@Tuples[{0,3},10]]},Table[SelectFirst[lst,Mod[#,n]==0&],{n,50}]] (* Harvey P. Dale, May 31 2025 *)
def A078242(n): if n > 0: for i in range(1,2**n): x = 3*int(bin(i)[2:]) if not x % n: return x return 0 # Chai Wah Wu, Dec 31 2014
For n = 7: a(7) = 15873 because 7 * 15873 = 111111. Repunit 111111 is the smallest repunit with prime factor 7.
Table[If[GCD[n, 10] > 1, 0, k = MultiplicativeOrder[10, 9*n]; (10^k - 1)/(9*n)], {n, 100}] (* T. D. Noe, May 08 2011 *)
a(n)=if(gcd(n,10)>1, 0, (10^znorder(Mod(10,9*n))-1)/9/n) \\ Charles R Greathouse IV, Aug 28 2016
s = With[{c = Rest[Union[FromDigits /@ Flatten[Table[Tuples[{1, 0}, i], {i, 10}], 1]]]}, Join[{0}, Flatten[Table[Select[c, Divisible[#, n] &, 1], {n, 120}]]]]; FromDigits[IntegerDigits@ #, 2] & /@ s (* Michael De Vlieger, Apr 29 2015, after Harvey P. Dale at A004290 *)
def A257345(n): if n > 0: for i in range(1, 2**n): x = int(format(i, 'b')) if not x % n: return int(str(x), 2) return 0 # Chai Wah Wu, Apr 29 2015
a078243 n = head [x | x <- tail a169967_list, mod x n == 0] -- Reinhard Zumkeller, Jan 10 2012
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