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.

A373347 Positive integers k such that A000120(k) > A001511(k).

Original entry on oeis.org

3, 5, 7, 9, 11, 13, 14, 15, 17, 19, 21, 22, 23, 25, 26, 27, 29, 30, 31, 33, 35, 37, 38, 39, 41, 42, 43, 45, 46, 47, 49, 50, 51, 53, 54, 55, 57, 58, 59, 60, 61, 62, 63, 65, 67, 69, 70, 71, 73, 74, 75, 77, 78, 79, 81, 82, 83, 85, 86, 87, 89, 90, 91, 92, 93, 94, 95, 97, 98, 99
Offset: 1

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Author

Paolo Xausa, Jun 01 2024

Keywords

Comments

Numbers whose binary expansion does not encode for any Schreier set (cf. A371176 and A373345).
All odd numbers > 1 are terms.

Crossrefs

Complement of A371176.
Cf. A000120, A001511, A008466, A373345, A373360 (first differences).

Programs

  • Mathematica
    Select[Range[100], DigitSum[#, 2] > IntegerExponent[#, 2] + 1 &]
  • PARI
    isok(k) = hammingweight(k) > valuation(2*k, 2); \\ Michel Marcus, Jun 07 2024
  • Python
    def isa(n): return (n - 1).bit_count() < ((n.bit_count() - 1) << 1)
    print([n for n in range(100) if isa(n)])  # Peter Luschny, Jun 07 2024
    

Formula

a(k) = 2^(n+1) - 1; a(k+1) = 2^(n+1) + 1, where k = A008466(n+1).