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.

A174933 a(n) = Sum_{d|n} A007955(d) * A000027(d) = Sum_{d|n} A007955(d) * (d), where A007955(m) = product of divisors of m.

Original entry on oeis.org

1, 5, 10, 37, 26, 230, 50, 549, 253, 1030, 122, 20998, 170, 2798, 3410, 16933, 290, 105449, 362, 161062, 9320, 10774, 530, 7984134, 3151, 17750, 19936, 617486, 842, 24304630, 962, 1065509, 36068, 39598, 42950, 362923273, 1370, 55238, 59498, 102561574
Offset: 1

Views

Author

Jaroslav Krizek, Apr 02 2010

Keywords

Examples

			For n = 4, A007955(n) = b(n): a(4) = b(1)*1 + b(2)*2 + b(4)*4 = 1*1 + 2*2 + 8*4 = 37.
		

Crossrefs

Cf. A007955.

Programs

  • Magma
    [&+[&*Divisors(d)*d:d in Divisors(n)]:n in [1..40]]; // Marius A. Burtea, Jan 05 2020
    
  • PARI
    a(n)={sumdiv(n, d, vecprod(divisors(d))*d)} \\ Andrew Howroyd, Jan 05 2020
    
  • Python
    from math import isqrt
    from sympy import divisor_count, divisors
    def A174933(n): return sum(isqrt(d)**(c+2) if (c:=divisor_count(d)) & 1 else d**(c//2+1) for d in divisors(n,generator=True)) # Chai Wah Wu, Jun 25 2022

Extensions

Terms a(31) and beyond from Andrew Howroyd, Jan 05 2020