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a(n) is the minimum positive integer j such that [j, j+n-1] does not contain any values of sigma(k) (i.e., sum of all positive divisors of k).
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%I #21 Mar 07 2024 20:08:51

%S 2,9,9,49,49,423,423,423,423,1333,1333,4425,4425,4425,4425,8763,8763,

%T 14089,14089,22825,22825,22825,22825,40291,40291,40291,40291,40291,

%U 40291,178705,178705,661285,661285,661285,661285,4543141,4543141,4543141,4543141,4543141,4543141,4543141,4543141,4543141,4543141,4543141,4543141

%N a(n) is the minimum positive integer j such that [j, j+n-1] does not contain any values of sigma(k) (i.e., sum of all positive divisors of k).

%H Donovan Johnson, <a href="/A109322/b109322.txt">Table of n, a(n) for n = 1..85</a> (terms < 10^10)

%H Art of Problem Solving, <a href="http://www.artofproblemsolving.com/Forum/viewtopic.php?t=26906">Gaps in {sigma(n)}...</a>

%Y Cf. A002191, A083531, A109323, A109324, A110875.

%K nonn

%O 1,1

%A _Max Alekseyev_ and _Jud McCranie_, Aug 08 2005