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A309811 (sigma, tau)-superchampion numbers: numbers k for which there is a positive exponent e such that sigma(k)/(k*tau(k)^e) >= sigma(j)/(j*tau(j)^e) for all j >= 1, where tau(k) is the number of divisors of k (A000005) and sigma(k) is their sum (A000203). 0
1, 2, 6, 12, 60, 120, 360, 2520, 5040, 55440, 720720, 2162160, 4324320, 73513440, 367567200, 6983776800, 160626866400, 321253732800, 9316358251200, 288807105787200, 2021649740510400, 74801040398884800, 224403121196654400, 9200527969062830400, 395622702669701707200 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..25.

Jean-Louis Nicolas, Quelques inégalités effectives entre des fonctions arithmétiques usuelles, Functiones et Approximatio, Vol. 39, No. 2 (2008), pp. 315-334. See section 3.

CROSSREFS

Cf. A000005, A000203, A002201, A004490.

Sequence in context: A263572 A004490 A224078 * A309233 A135060 A185021

Adjacent sequences:  A309808 A309809 A309810 * A309812 A309813 A309814

KEYWORD

nonn

AUTHOR

Amiram Eldar, Aug 25 2019

STATUS

approved

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Last modified November 21 22:35 EST 2019. Contains 329383 sequences. (Running on oeis4.)