%I #9 Oct 27 2023 22:00:45
%S 1,4,10,9,11,30,10,20,40,32,16,65,13,42,82,46,12,96,26,82,106,46,18,
%T 143,57,70,114,88,40,214,26,66,136,88,120,244,30,60,160,171,47,256,36,
%U 150,266,96,40,286,88,176,226,124,12,24,342,170,230,222,94,34,443,71
%N Second differences of sigma(n) that are negative.
%F a(n) = A053223(A053229(n)).
%p with (numtheory): f := [seq( sigma(i+2)  sigma(i+1)  (sigma(i+1)  sigma(i)), i=1..200)];
%p seq(`if`(f[i] < 0,f[i],print( )), i=1..200);
%t Abs[Select[Differences[DivisorSigma[1,Range[200]],2],Negative]] (* _Harvey P. Dale_, Aug 13 2015 *)
%Y Cf. A000203, A053223, A053247.
%K nonn
%O 1,2
%A _Asher Auel_, Jan 11 2000
