OFFSET
1,3
LINKS
Michel Marcus, Table of n, a(n) for n = 1..10000
MATHEMATICA
Array[#+#2-#3&@@DivisorSigma[1, {#, #+1, #+2}]&, 100] (* Giorgos Kalogeropoulos, Oct 29 2021 *)
PROG
(PARI) a(n) = sigma(n)+sigma(n+1) - sigma(n+2);
CROSSREFS
KEYWORD
sign
AUTHOR
Michel Marcus, Oct 29 2021
STATUS
approved