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.

A278782 Numbers m such that A000041(m) is of the form 2^5 * k for odd k.

Original entry on oeis.org

70, 179, 262, 278, 419, 561, 682, 698, 767, 879, 1147, 1238, 1273, 1317, 1362, 1364, 1378, 1450, 1478, 1499, 1509, 1548, 1590, 1638, 1668, 1711, 1752, 1781, 1838, 1949, 2170, 2187, 2300, 2317, 2334, 2382, 2408, 2447, 2463, 2499, 2551, 2669, 2695, 2788, 2926
Offset: 1

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Author

Colin Barker, Nov 28 2016

Keywords

Comments

Numbers m such that A278478(m) = 5.
Also numbers m such that A000041(m) has five times as many even divisors as odd divisors.

Crossrefs

Positions of 5's in A278478.

Programs

  • Mathematica
    Select[Range[500], IntegerExponent[PartitionsP[#], 2] == 5 &] (* Amiram Eldar, May 25 2024 *)
  • PARI
    isok(n) = valuation(numbpart(n), 2)==5;
    select(n->isok(n), vector(3000, n, n))

Formula

A000041(a(n)) = A278199(n).