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.

A267085 Numbers such that the number formed by digits in even position divides, or is divisible by, the number formed by the digits in odd position; both must be nonzero.

Original entry on oeis.org

11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 24, 26, 28, 31, 33, 36, 39, 41, 42, 44, 48, 51, 55, 61, 62, 63, 66, 71, 77, 81, 82, 84, 88, 91, 93, 99, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 122, 124, 126, 128, 132, 135, 138, 142, 146, 150, 155, 162, 168, 174, 186, 198
Offset: 1

Views

Author

Eric Angelini and M. F. Hasler, Jan 10 2016

Keywords

Comments

Termed "integears" by Eric Angelini. See A267086 for the "extended version" where zero is allowed.

Crossrefs

See also A080463, A080464 and A080465.

Programs

  • Mathematica
    Select[Range[10, 200], Or[If[#2 == 0, False, Mod[#1, #2] == 0], If[#2 == 0, False, Mod[#2, #1] == 0]] & @@ {FromDigits@ Extract[#, Range[1, Length@ #, 2] /. x_Integer -> {x}], FromDigits@ Extract[#, Range[2, Length@#, 2] /. x_Integer -> {x}]} &@ IntegerDigits@ # &] (* Michael De Vlieger, Jan 21 2016 *)
  • PARI
    is(n,d=digits(n))={n=d*matrix(#d,2,z,s,if(z==Mod(s,2),10^((#d-z)\2))); n[2] && (n[1]%n[2]==0 || n[2]%n[1]==0)}