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).

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

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

Cf. A001227, A082477.

Sequence in context: A117546 A274196 A096811 * A279060 A324119 A083382

Adjacent sequences: A082475 A082476 A082477 * A082479 A082480 A082481

Keyword

nonn

Author

Benoit Cloitre, Apr 27 2003

Status

approved