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A234801 Start of a record-breaking run of consecutive arithmetic numbers. 0
1, 5, 19, 41, 181, 347, 1497, 4955, 6026, 17101, 55923, 80897, 131729, 167585, 393033, 673859, 1484603, 2761381, 9220483, 13694929, 47390331, 82626389, 108980139, 717512595, 972975322, 1333553577, 2547417520, 3033935561, 21214519093, 24441006509, 261703848520 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A number is called arithmetic (A003601) if the average of its divisors is integer.

The run that starts at 261703848520 has length 132.

LINKS

Table of n, a(n) for n=1..31.

EXAMPLE

The first arithmetic numbers are 1, 3, 5, 6, 7, 11, hence the first two terms of the sequence are 1 and 5.

MATHEMATICA

arQ[n_] := 0 == Mod @@ (DivisorSigma[#, n] & /@ {1, 0}); r=c=n=0; While[True, If[arQ[++n], c++, If[c>r, r=c; Print@{c, n-c}]; c=0]]

CROSSREFS

Cf. A003601.

Sequence in context: A033622 A091568 A147307 * A089148 A098319 A022267

Adjacent sequences:  A234798 A234799 A234800 * A234802 A234803 A234804

KEYWORD

nonn

AUTHOR

Giovanni Resta, Jan 16 2014

STATUS

approved

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Last modified June 17 19:10 EDT 2019. Contains 324198 sequences. (Running on oeis4.)