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.

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