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.

Showing 1-3 of 3 results.

A352379 Numbers k such that no nonzero digit of 2*k divides 2*k.

Original entry on oeis.org

17, 19, 23, 27, 28, 29, 34, 37, 38, 39, 43, 47, 49, 154, 167, 169, 173, 178, 179, 185, 187, 188, 190, 193, 194, 197, 199, 203, 215, 217, 223, 227, 229, 233, 235, 237, 239, 245, 247, 249, 253, 254, 268, 269, 277, 278, 279, 283, 289, 293, 294, 298, 299, 317, 319, 323, 328, 329, 334, 335, 337, 338, 343
Offset: 1

Views

Author

Eric Angelini and Carole Dubois, Mar 14 2022

Keywords

Comments

There are no terms between and including 500 and 1500 and there are no terms between and including 5000 and 15000. - Harvey P. Dale, Apr 05 2025

Examples

			a(1) = 17 and 2*17 = 34 is not divisible by 3 or 4;
a(2) = 19 and 2*19 = 38 is not divisible by 3 or 8;
a(3) = 23 and 2*23 = 46 is not divisible by 4 or 6;
a(4) = 27 and 2*27 = 54 is not divisible by 5 or 4; etc.
31 is not in the sequence as 2*31 = 62 is divisible by 2.

Links

Crossrefs

Cf. A038772, A352380, A352381, A352382.

Programs

  • Mathematica
    q[n_] := AllTrue[IntegerDigits[2*n], # == 0 || !Divisible[2*n, #] &]; Select[Range[350], q] (* Amiram Eldar, Mar 14 2022 *)
nnzdQ[n_]:=NoneTrue[Mod[2 n,Select[IntegerDigits[2 n],#!=0&]],#==0&]; Select[Range[350],nnzdQ] (* Harvey P. Dale, Apr 05 2025 *)
  • Python
    def ok(n): return not any(2*n%int(d)==0 for d in set(str(2*n)) if d!='0')
print([k for k in range(1, 344) if ok(k)]) # Michael S. Branicky, Mar 14 2022

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

Cf. A038772, A352379, A352381, A352382.

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

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

Cf. A038772, A352379, A352380, A352381.

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
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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