OFFSET
1,1
COMMENTS
There are few odd terms in the sequence, first one is 18015.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Vaclav Kotesovec, Plot of a(n)/n for n = 1..1600000
FORMULA
It seems that a(n) is asymptotic to c*n with 14<=c<=16. [This conjecture is false, see plot. - Vaclav Kotesovec, Feb 16 2019]
MATHEMATICA
Select[Range[1, 1000], DivisorSigma[0, #] < DivisorSigma[0, #+1] && EulerPhi[#] < EulerPhi[#+1]&] (* Vaclav Kotesovec, Feb 16 2019 *)
Position[Partition[Table[{DivisorSigma[0, n], EulerPhi[n]}, {n, 1100}], 2, 1], _?(#[[1, 1]]<#[[2, 1]]&&#[[1, 2]]<#[[2, 2]]&), 1, Heads->False]//Flatten (* Harvey P. Dale, Dec 11 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Sep 07 2002
STATUS
approved