OFFSET
1,3
COMMENTS
The number of solutions is always even because k=n/2 cannot be a solution for even n.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..16384
MATHEMATICA
a[n_] := Select[Range[n-1], DivisorSigma[1, n]==DivisorSigma[1, n-# ]+DivisorSigma[1, # ]&]; Table[Length[a[n]], {n, 150}]
PROG
(PARI) A110177(n) = { my(x=sigma(n)); sum(k=1, n-1, (x == (sigma(k)+sigma(n-k)))); }; \\ Antti Karttunen, Feb 20 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
T. D. Noe, Jul 15 2005
STATUS
approved