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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A238989 Numbers that are not odiousfree*evilfree. The complement of A237417.

Original entry on oeis.org

1, 2, 4, 7, 8, 11, 13, 14, 16, 19, 22, 25, 26, 28, 31, 32, 37, 38, 41, 44, 47, 49, 50, 52, 56, 59, 61, 62, 64, 67, 69, 73, 74, 75, 76, 77, 79, 81, 82, 87, 88, 91, 94, 97, 98, 100, 103, 104, 107, 109, 112, 115, 118, 121, 122, 124, 125, 127, 128
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Mar 08 2014

Keywords

Crossrefs

Cf. A000069 (odious numbers), A001969 (evil numbers), A093688 (1 together with odiousfree numbers), A093696 (evilfree numbers), A237417 (odiousfree*evilfree numbers).

Programs

  • Mathematica
    odFreeQ[n_] := AllTrue[Rest @ Divisors[n], EvenQ[DigitCount[#, 2, 1]] &]; evFreeQ[n_] := AllTrue[Divisors[n], OddQ[DigitCount[#, 2, 1]] &]; m = 100; o = Select[Range[2, m], odFreeQ]; e = Select[Range[m], evFreeQ]; Complement[Range[m], Union @ Select[Times @@@ Tuples[{o, e}], # <= m &]] (* Amiram Eldar, Oct 16 2020 *)
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