OFFSET
1,7
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
FORMULA
a(2^n-1) = A001227(n).
MATHEMATICA
a[n_] := DivisorSum[n, 1 &, Divisible[n+1, #+1] && Divisible[n+2, #+2] &]; Array[a, 100] (* Amiram Eldar, Jun 03 2022 *)
PROG
(PARI) a(n)=sumdiv(n, d, if((n+1)%(d+1)+(n+2)%(d+2), 0, 1))
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Apr 27 2003
STATUS
approved