cp's OEIS Frontend

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.

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A082943 Positive numbers not divisible by any of their digits nor by the sum of their digits.

Original entry on oeis.org

23, 29, 34, 37, 38, 43, 46, 47, 49, 53, 56, 57, 58, 59, 67, 68, 69, 73, 74, 76, 78, 79, 83, 86, 87, 89, 94, 97, 98, 223, 227, 229, 233, 239, 249, 253, 257, 259, 263, 267, 269, 277, 283, 289, 293, 299, 323, 329, 334, 337, 338, 343, 346, 347, 349, 353, 356
Offset: 1

Views

Author

Meenakshi Srikanth (menakan_s(AT)yahoo.com), Apr 30 2003

Keywords

Comments

The definition implies that no digit is zero. - N. J. A. Sloane, Mar 27 2025

Examples

			38 is neither divisible by 3 nor 8 nor 11 (i.e. 3+8).
		

Crossrefs

Programs

  • Maple
    filter:= proc(n) local L;
      L:= convert(n,base,10);
      not member(0,L) and not ormap(t -> n mod t = 0, [op(L),convert(L,`+`)])
    end proc:
    select(filter, [$1..1000]); # Robert Israel, Mar 19 2025
  • Mathematica
    test1[n_] := Module[{dig = IntegerDigits[n]}, Union[Table[IntegerQ[n/dig[[i]]], {i, Length[dig]}]]] == {False};
    test2[n_] := Module[{dig = IntegerDigits[n]}, Not[IntegerQ[n/Sum[dig[[i]], {i, Length[dig]}]]]];
    Table[If[test1[n] && test2[n], n, 0], {n, 200}] // Union // Rest (* José María Grau Ribas, Feb 17 2010 *)
    ndQ[n_]:=Module[{idn=IntegerDigits[n]},FreeQ[idn,0]&&NoneTrue[n/ Join[ idn, {Total[idn]}],IntegerQ]]; Select[Range[2000],ndQ] (* Harvey P. Dale, Oct 19 2016 *)

Extensions

More terms from Harvey P. Dale, Oct 19 2016

A352380 Numbers k such that no nonzero digit of 3*k divides 3*k.

Original entry on oeis.org

9, 18, 19, 23, 26, 29, 69, 83, 89, 143, 149, 158, 159, 163, 166, 169, 186, 193, 196, 199, 203, 209, 219, 223, 229, 233, 236, 249, 253, 258, 260, 263, 269, 283, 286, 289, 290, 293, 298, 299, 319, 323, 326, 669, 683, 689, 743, 759, 763, 803, 809, 823, 829, 833, 849, 853, 859, 863, 869, 883, 893, 899
Offset: 1

Views

Author

Eric Angelini and Carole Dubois, Mar 14 2022

Keywords

Examples

			a(1) = 9 and 3*9 = 27 is not divisible by 2 or 7;
a(2) = 18 and 3*18 = 54 is not divisible by 5 or 4;
a(3) = 19 and 3*19 = 57 is not divisible by 5 or 7;
a(4) = 23 and 3*23 = 69 is not divisible by 6 or 9; etc.
31 is not in the sequence as 3*31 = 93 is divisible by 3.
		

Crossrefs

Programs

  • Mathematica
    q[n_] := AllTrue[IntegerDigits[3*n], # == 0 || !Divisible[3*n, #] &]; Select[Range[900], q] (* Amiram Eldar, Mar 14 2022 *)
  • Python
    def ok(n): return not any(3*n%int(d)==0 for d in set(str(3*n)) if d!='0')
    print([k for k in range(1, 900) if ok(k)]) # Michael S. Branicky, Mar 14 2022

A352381 Numbers k such that no nonzero digit of 4*k divides 4*k.

Original entry on oeis.org

14, 17, 19, 77, 89, 94, 95, 97, 127, 134, 139, 147, 149, 164, 167, 169, 177, 184, 190, 194, 195, 197, 199, 209, 215, 217, 227, 239, 244, 245, 247, 764, 767, 769, 827, 839, 844, 845, 847, 877, 884, 889, 899, 914, 917, 919, 925, 934, 940, 944, 947, 949, 959, 965, 967, 977, 989, 995, 997, 1259, 1264, 1267
Offset: 1

Views

Author

Eric Angelini and Carole Dubois, Mar 14 2022

Keywords

Examples

			a(1) = 14 and 4*14 = 56 is not divisible by 5 or 6;
a(2) = 17 and 4*17 = 68 is not divisible by 6 or 8;
a(3) = 19 and 4*19 = 76 is not divisible by 7 or 6;
a(4) = 77 and 4*77 = 308 is not divisible by 3, 0 or 8; etc.
26 is not in the sequence as 4*26 = 104 is divisible by 1 (and 4).
		

Crossrefs

Programs

  • Mathematica
    q[n_] := AllTrue[IntegerDigits[4*n], # == 0 || !Divisible[4*n, #] &]; Select[Range[1270], q] (* Amiram Eldar, Mar 14 2022 *)
  • Python
    def ok(n): return not any(4*n%int(d)==0 for d in set(str(4*n)) if d!='0')
    print([k for k in range(1, 978) if ok(k)]) # Michael S. Branicky, Mar 14 2022

A352382 Numbers k such that no nonzero digit of 5*k divides 5*k.

Original entry on oeis.org

74, 76, 86, 94, 98, 134, 146, 152, 156, 158, 166, 172, 174, 178, 194, 196, 614, 674, 676, 686, 694, 698, 734, 740, 746, 752, 754, 758, 766, 772, 778, 794, 796, 806, 814, 818, 866, 874, 878, 886, 894, 898, 926, 934, 938, 946, 954, 958, 974, 978, 986, 998, 1214, 1276, 1286, 1294, 1298, 1334, 1340
Offset: 1

Views

Author

Eric Angelini and Carole Dubois, Mar 14 2022

Keywords

Comments

Only even terms (see the last line of the Example section to understand why).

Examples

			a(1) = 74 and 5*74 = 370 is not divisible by 3, 7 or 0;
a(2) = 76 and 5*76 = 380 is not divisible by 3, 8 or 0;
a(3) = 86 and 5*86 = 430 is not divisible by 4, 3 or 0;
a(4) = 94 and 5*94 = 470 is not divisible by 4, 7 or 0; etc.
93 is not in the sequence as 5*93 = 465 is divisible by 5.
		

Crossrefs

Programs

  • Mathematica
    q[n_] := AllTrue[IntegerDigits[5*n], # == 0 || !Divisible[5*n, #] &]; Select[Range[1340], q] (* Amiram Eldar, Mar 14 2022 *)
  • Python
    def ok(n): return not any(5*n%int(d)==0 for d in set(str(5*n)) if d!='0')
    print([k for k in range(1, 1277) if ok(k)]) # Michael S. Branicky, Mar 14 2022

A382239 Numbers not divisible by any of their digits nor by the sum of their digits. Digit 0 is allowed (and does not divide anything).

Original entry on oeis.org

23, 29, 34, 37, 38, 43, 46, 47, 49, 53, 56, 57, 58, 59, 67, 68, 69, 73, 74, 76, 78, 79, 83, 86, 87, 89, 94, 97, 98, 203, 223, 227, 229, 233, 239, 249, 253, 257, 259, 263, 267, 269, 277, 283, 289, 293, 299, 307, 323, 329, 334, 337, 338, 343, 346, 347, 349, 353, 356, 358, 359, 367, 373, 374, 376
Offset: 1

Views

Author

Robert Israel, Mar 19 2025

Keywords

Comments

From a suggestion by Sergio Pimentel.

Examples

			a(5) = 38 is included because 38 is not divisible by 3, 8 or 3 + 8 = 11.
a(30) = 203 is included because 203 is not divisible by 2, 0, 3 or 2 + 0 + 3 = 5.
		

Crossrefs

Subsequence of A052383.

Programs

  • Maple
    filter:= proc(n) local L;
      L:= subs(0=NULL,convert(n,base,10));
      not ormap(t -> n mod t = 0, [op(L),convert(L,`+`)])
    end proc:
    select(filter, [$1..1000]);
  • Mathematica
    s= {};Do[t=Select[IntegerDigits[n],#>0&];AppendTo[t,Total[t]];If[NoneTrue[t,Mod[n,#]==00&],AppendTo[s,n]],{n,376}];s (* James C. McMahon, Mar 21 2025 *)
  • Python
    def ok(n):
        d = list(map(int, str(n)))
        return (s:=sum(d)) and n%s!=0 and all(n%di!=0 for di in set(d)-{0})
    print([k for k in range(1, 377) if ok(k)]) # Michael S. Branicky, Apr 01 2025

Formula

n^k << a(n) < 2^n for n > 5 where k = log(10)/log(9). - Charles R Greathouse IV, Mar 20 2025

A244356 Numbers n such that n and n+1 are not divisible by any of their nonzero digits.

Original entry on oeis.org

37, 46, 53, 56, 57, 58, 67, 68, 73, 78, 86, 97, 307, 337, 346, 358, 373, 376, 379, 388, 397, 406, 429, 433, 446, 457, 466, 469, 473, 477, 478, 489, 493, 498, 506, 507, 508, 538, 553, 556, 557, 558, 577, 578, 586, 587, 588, 596, 597, 598, 646, 656, 657, 658, 667, 668, 669
Offset: 1

Views

Author

Derek Orr, Jun 26 2014

Keywords

Comments

This is a subsequence of A038772.
All numbers end in a 3, 6, 7, 8, or 9.

Examples

			37 is not divisible by 3 or 7 and 38 is not divisible by 3 or 8. Thus 37 is a member of this sequence.
		

Crossrefs

Programs

  • Maple
    filter:= proc(n) local L;
      L:= convert(convert(n,base,10), set) minus {0};
      not ormap(t -> n mod t = 0, L)
    end proc:
    B:= select(filter, {$1..1000}):
    sort(convert(B intersect map(`-`,B,1), list)); # Robert Israel, Dec 08 2019
  • Python
    def a(n):
      for i in range(10**3):
        tot = 0
        for k in range(i,i+n):
          c = 0
          for b in str(k):
            if b != '0':
              if k%int(b)!=0:
                c += 1
          if c == len(str(k))-str(k).count('0'):
            tot += 1
        if tot == n:
          print(i,end=', ')
    a(2)

A244357 Numbers n such that n, n+1, and n+2 are not divisible by any of their nonzero digits.

Original entry on oeis.org

56, 57, 67, 477, 506, 507, 556, 557, 577, 586, 587, 596, 597, 656, 657, 667, 668, 697, 757, 758, 778, 787, 788, 857, 858, 866, 867, 868, 877, 897, 956, 957, 976, 977, 978, 4077, 4097, 4457, 4477, 4497, 4657, 4677, 4757, 4857, 4897, 4997, 5056, 5057, 5066, 5067, 5077, 5096
Offset: 1

Views

Author

Derek Orr, Jun 26 2014

Keywords

Comments

This is a subsequence of A244356.
All numbers end in a 6, 7, or 8.

Examples

			56, 57, and 58 are not divisible by their digits. Thus, 56 is a member of this sequence.
		

Crossrefs

Programs

  • Mathematica
    SequencePosition[Table[If[NoneTrue[n/Select[IntegerDigits[n],#>0&],IntegerQ], 1,0],{n,5100}],{1,1,1}][[All,1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Mar 15 2018 *)
  • Python
    def a(n):
      for i in range(10**4):
        tot = 0
        for k in range(i,i+n):
          c = 0
          for b in str(k):
            if b != '0':
              if k%int(b)!=0:
                c += 1
          if c == len(str(k))-str(k).count('0'):
            tot += 1
        if tot == n:
          print(i,end=', ')
    a(3)

A244358 Numbers k such that k, k+1, k+2, and k+3 are not divisible by any of their nonzero digits.

Original entry on oeis.org

56, 506, 556, 586, 596, 656, 667, 757, 787, 857, 866, 867, 956, 976, 977, 5056, 5066, 5096, 5506, 5666, 5756, 5776, 5876, 5906, 5986, 5996, 6056, 6067, 6506, 6697, 6986, 7057, 7556, 7576, 7597, 7757, 7786, 7787, 7876, 7897, 7906, 7976, 7996, 8066, 8067, 8506, 8596, 8666, 8697
Offset: 1

Views

Author

Derek Orr, Jun 26 2014

Keywords

Comments

This is a subsequence of A244357.
All numbers end in a 6 or 7.

Examples

			56, 57, 58, and 59 are not divisible by any of their digits. Thus, 56 is a member of this sequence.
		

Crossrefs

Programs

  • Mathematica
    SequencePosition[Table[If[NoneTrue[n/(IntegerDigits[n]/.(0->Nothing)),IntegerQ],1,0],{n,9000}],{1,1,1,1}][[;;,1]] (* Harvey P. Dale, Jun 06 2025 *)
  • Python
    def a(n):
      for i in range(10**4):
        tot = 0
        for k in range(i,i+n):
          c = 0
          for b in str(k):
            if b != '0':
              if k%int(b)!=0:
                c += 1
          if c == len(str(k))-str(k).count('0'):
            tot += 1
        if tot == n:
          print(i,end=', ')
    a(4)

A382237 Numbers that are not divisible by the sum of any subset of their digits.

Original entry on oeis.org

23, 29, 34, 37, 38, 43, 46, 47, 49, 53, 56, 57, 58, 59, 67, 68, 69, 73, 74, 76, 78, 79, 83, 86, 87, 89, 94, 97, 98, 203, 223, 227, 229, 233, 239, 249, 253, 257, 263, 267, 269, 277, 283, 293, 299, 307, 323, 329, 334, 337, 338, 346, 347, 349, 353, 356, 358, 359, 367, 373, 376, 377, 379, 380, 383, 386, 388, 389, 394, 397, 398, 403
Offset: 1

Views

Author

Sergio Pimentel, Mar 19 2025

Keywords

Comments

This sequence has density zero since no numbers with the digit '1' are in it. The sequence is infinite. Example: Numbers like 23, 203, 2003, 20003, etc. are included because none of them is divisible by 2, 3, or 5.
Conjecture: after a sufficiently large n this sequence grows faster than the prime numbers.

Examples

			358 is in the sequence because it can't be divided by 3, 5, 8, (3+5)=8, (3+8)=11, (5+8)=13 or (3+5+8)=16.
289 is not in the sequence because it can be divided by (8+9)=17.
		

Crossrefs

Programs

  • Maple
    filter:= proc(n) local L,S;
      L:= convert(n,base,10);
      andmap(s -> s=0 or n mod s <> 0, map(convert,combinat:-choose(L),`+`))
    end proc:
    select(filter, [$1..1000]); # Robert Israel, Mar 19 2025
  • PARI
    isok(k) = my(d=digits(k)); forsubset(#d, s, my(ss=sum(i=1, #s, d[s[i]])); if (ss && !(k % sum(i=1, #s, d[s[i]])), return(0))); return(1); \\ Michel Marcus, Mar 27 2025
    
  • Python
    from itertools import chain, combinations
    def powerset(s): # skipping empty set
        return chain.from_iterable(combinations(s, r) for r in range(1, len(s)+1))
    def ok(n): return all(n%t!=0 for s in powerset(list(map(int, str(n)))) if (t:=sum(s))>0)
    print([k for k in range(1, 404) if ok(k)]) # Michael S. Branicky, Apr 01 2025

A383749 Positive numbers k whose decimal expansion does not contain the decimal expansion of any proper divisor of k.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 23, 27, 29, 34, 37, 38, 43, 46, 47, 49, 53, 54, 56, 57, 58, 59, 67, 68, 69, 73, 74, 76, 78, 79, 83, 86, 87, 89, 94, 97, 98, 203, 207, 209, 223, 227, 229, 233, 239, 247, 249, 253, 257, 259, 263, 267, 269, 277, 283, 289, 293, 299, 307
Offset: 1

Views

Author

Rémy Sigrist, May 08 2025

Keywords

Comments

Also fixed points of A121042.
This sequence is infinite as it contains A173041.
a(n) > 5 contains no decimal digit 1 and does not end in 2 or 5. - Michael S. Branicky, May 11 2025

Examples

			The proper divisors of 54 are 1, 2, 3, 6, 9, 18 and 27; none of them appear in the decimal expansion of 54 so 54 belongs to this sequence.
		

Crossrefs

A038603 and A173041 are subsequences.

Programs

  • Mathematica
    A383749Q[k_] := SelectFirst[Divisors[k], StringContainsQ[IntegerString[k], IntegerString[#]] &] == k;
    Select[Range[500], A383749Q] (* Paolo Xausa, May 12 2025 *)
  • PARI
    is(n, base = 10) = {
        my (d = digits(n, base));
        for (i = 1, #d,
            if (d[i],
                for (j = i, #d,
                    if ((i!=1 || j!=#d) && n % fromdigits(d[i..j], base)==0,
                        return (0);););););
        return (1);}
    
  • Python
    from itertools import count, islice
    from sympy import divisors
    def A383749_gen(startvalue=1): # generator of terms >= startvalue
        return filter(lambda n:not any(dA383749_list = list(islice(A383749_gen(),40)) # Chai Wah Wu, May 10 2025
    
  • Python
    def ok(n):
        s = str(n)
        subs = (s[i:j] for i in range(len(s)) for j in range(i+1, len(s)+1) if s[i]!='0')
        return n and not any(n%v == 0 for ss in subs if n > (v:=int(ss)) > 0)
    print([k for k in range(308) if ok(k)]) # Michael S. Branicky, May 11 2025
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