OFFSET
1,1
COMMENTS
a(17) > 10^13. - Giovanni Resta, May 09 2020
EXAMPLE
21 is a term since s(21) = 11 and s(19) + s(20) = 1 + 10 = 11.
MATHEMATICA
usigma[1] = 1; usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); s[n_] := usigma[n] - n; Select[Range[3, 6*10^5], s[#] == s[# - 1] + s[# - 2] &]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Mar 04 2020
EXTENSIONS
a(12)-a(16) from Giovanni Resta, May 09 2020
STATUS
approved