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A074844 Largest difference between consecutive divisors of n is equal to the sum of divisors of n except 1 and n. 1
4, 345, 6489, 88473 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

No other term < 600000. - Emeric Deutsch, Aug 04 2005

No more terms < 10^9. - Lars Blomberg, Jun 04 2013

If p = 5^k - 2 is a prime > 3, then 3*p*(p+2)/5 is in this sequence (see A109080). - Charlie Neder, Oct 13 2018

a(5) > 10^13. - Giovanni Resta, Feb 15 2020

LINKS

Table of n, a(n) for n=1..4.

EXAMPLE

The divisors of 345 are [1, 3, 5, 15, 23, 69, 115, 345] and the largest difference between consecutive divisors is 345-115 = 230; the sum of divisors except 1 and 345 are 3+5+15+23+69+115 = 230.

MAPLE

with(numtheory): a:=proc(n) local div: div:=divisors(n): if max(seq(div[j]-div[j-1], j=2..tau(n)))=sigma(n)-1-n then n else fi end: seq(a(n), n=1..100000); # Emeric Deutsch, Aug 04 2005

CROSSREFS

Cf. A048050, A060681.

Sequence in context: A069884 A332134 A283101 * A225207 A052391 A214182

Adjacent sequences:  A074841 A074842 A074843 * A074845 A074846 A074847

KEYWORD

nonn,more

AUTHOR

Jason Earls, Sep 10 2002

EXTENSIONS

More terms from Emeric Deutsch, Aug 04 2005

STATUS

approved

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Last modified October 20 09:24 EDT 2021. Contains 348100 sequences. (Running on oeis4.)