A073023 Number of solutions to the equation n^x==1 (mod x), 1<=x<=n.

1, 1, 2, 2, 3, 2, 5, 2, 4, 3, 7, 2, 8, 2, 6, 5, 7, 2, 11, 2, 8, 5, 11, 2, 12, 3, 9, 4, 14, 2, 18, 2, 7, 6, 12, 5, 16, 2, 10, 6, 19, 2, 22, 2, 9, 9, 16, 2, 19, 3, 13, 6, 18, 2, 20, 5, 14, 7, 21, 2, 28, 2, 10, 9, 17, 5, 29, 2, 17, 6, 31, 2, 23, 2, 10, 9, 23, 5, 32, 2, 16, 5, 26, 2, 28, 6, 14, 9

Offset

1,3

Links

Table of n, a(n) for n=1..88.

Formula

Conjecture: for n>100, Sum_{k=1..n} a(k) > n^(3/2).

Prog

(PARI) a(n)=sum(i=1, n, if((n^i-1)%i, 0, 1))

Crossrefs

Sequence in context: A285573 A325339 A010846 * A378772 A173754 A180125

Adjacent sequences: A073020 A073021 A073022 * A073024 A073025 A073026

Keyword

easy,nonn

Author

Benoit Cloitre, Aug 21 2002

Status

approved