OFFSET
1,5
COMMENTS
The first 3 occurs at n=4340. - R. J. Mathar, Jul 08 2015
LINKS
R. J. Mathar, Table of n, a(n) for n = 1..1000
FORMULA
Asymptotic mean: lim_{n->oo} (1/n) Sum_{k=1..n} a(k) = 1/A318172 = 1.3291... - Amiram Eldar, Oct 21 2020
EXAMPLE
a(1) = 1 because 2-1 = 1.
a(5) = 2 because 7-5 = 2.
MAPLE
MATHEMATICA
Differences@ Select[Range@ 105, DivisorSigma[1, #] < 2 # &] (* Michael De Vlieger, Jun 29 2018 *)
PROG
(GAP) A:=Filtered([1..100], n->Sigma(n)<2*n);; a:=List([1..Length(A)-1], i->A[i+1]-A[i]); # Muniru A Asiru, Jun 26 2018
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jason G. Wurtzel, Nov 25 2006
STATUS
approved