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A082478
Number of divisors d of n such that (d+1) is a divisor of (n+1) and (d+2) a divisor of (n+2).
2
1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 2, 2, 2, 1, 1, 2, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 1, 1
OFFSET
1,7
LINKS
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
Sequence in context: A117546 A274196 A096811 * A279060 A324119 A083382
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Apr 27 2003
STATUS
approved