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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A334809 a(n) = Product_{d|n} lcm(sigma(d), pod(d)) where sigma(k) is the sum of divisors of k (A000203) and pod(k) is the product of divisors of k (A007955).

Original entry on oeis.org

1, 6, 12, 336, 30, 2592, 56, 322560, 4212, 162000, 132, 1755758592, 182, 395136, 648000, 10239344640, 306, 68976790272, 380, 1524096000000, 9483264, 3449952, 552, 2796089100573081600, 116250, 15502032, 122821920, 485745426432, 870, 102036672000000000, 992
Offset: 1

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Author

Jaroslav Krizek, Aug 01 2020

Keywords

Examples

			a(6) = lcm(sigma(1), pod(1)) * lcm(sigma(2), pod(2)) * lcm(sigma(3), pod(3)) * lcm(sigma(6), pod(6)) = lcm(1, 1) * lcm(3, 2) * lcm(4, 3) * lcm(12, 36) = 1 * 6 * 12 * 36 = 2592.
		

Crossrefs

Cf. A334794 (Sum_{d|n} lcm(sigma(d), pod(d))), A334731 (Product_{d|n} gcd(sigma(d), pod(d))).
Cf. A000203(sigma(n)), A007955 (pod(n)), A324529 (lcm(sigma(n), pod(n))).

Programs

  • Magma
    [&*[LCM(&+Divisors(d), &*Divisors(d)): d in Divisors(n)]: n in [1..100]]

Formula

a(p) = p^2 + p for p = primes (A000040).
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