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A308574 Numbers between a pair of consecutive highly abundant numbers (A002093) having the same sum of divisors as the lesser one. 0
672, 2016, 69300, 146160, 207900, 1627920, 8316000, 9828000, 38253600, 60147360, 105814800, 158004000, 726818400, 95935039200, 191870078400, 2206505901600, 3463953292800, 3800093497200, 4413011803200, 7600186994400, 8826023606400 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Define "largely abundant numbers" to be numbers k such that sigma(k) >= sigma(j) for all j < k. This sequence gives all the largely abundant numbers that are not highly abundant numbers.

Analogous to A244353 as A002093 is analogous to A002182.

No more terms below 10^10.

a(22) > 10^13. - Giovanni Resta, Jul 02 2019

LINKS

Table of n, a(n) for n=1..21.

EXAMPLE

672 is in the sequence since 660 < 672 < 720, (660, 720) are a pair of consecutive highly abundant numbers, and sigma(672) = sigma(660) = 2016.

MATHEMATICA

s={}; sm=0; Do[s1=DivisorSigma[1, n]; If[s1==sm, AppendTo[s, n]]; If[s1>sm, sm=s1], {n, 1, 10^5}]; s

CROSSREFS

Cf. A002093, A002182, A067128, A244353.

Sequence in context: A057695 A233315 A157363 * A234732 A057805 A057796

Adjacent sequences:  A308571 A308572 A308573 * A308575 A308576 A308577

KEYWORD

nonn,more

AUTHOR

Amiram Eldar, Jun 08 2019

EXTENSIONS

a(14)-a(21) from Giovanni Resta, Jul 02 2019

STATUS

approved

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Last modified October 26 14:28 EDT 2021. Contains 348267 sequences. (Running on oeis4.)