A344773 Number of divisors d of n for which A342915(d) = A342915(n), where A342915(n) = gcd(1+n, psi(n)).

1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 4, 1, 2, 1, 3, 1, 3, 1, 2, 1, 2, 1, 5, 1, 2, 2, 3, 1, 4, 1, 3, 1, 2, 1, 6, 1, 2, 1, 4, 1, 3, 1, 1, 2, 2, 1, 7, 1, 2, 2, 3, 1, 4, 1, 4, 1, 2, 1, 7, 1, 2, 1, 4, 2, 4, 1, 2, 1, 3, 1, 8, 1, 2, 2, 3, 1, 3, 1, 1, 2, 2, 1, 7, 1, 2, 1, 4, 1, 6, 1, 2, 1, 2, 1, 8, 1, 3, 2, 4, 1, 4, 1, 1, 2

Offset

1,4

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Formula

a(n) = Sum_{d|n} [A342915(d) = A342915(n)], where [ ] is the Iverson bracket.

a(n) <= A344771(n).

Prog

(PARI)
A001615(n) = if(1==n, n, my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[i, 2] + f[i, 1]^(f[i, 2]-1))); \\ After code in A001615
A342915(n) = gcd(1+n, A001615(n));
A344773(n) = { my(x=A342915(n)); sumdiv(n, d, A342915(d)==x); };

Crossrefs

Cf. A001615, A342915, A344771.

Cf. also A344774.

Sequence in context: A185216 A247976 A280986 * A103689 A245039 A161313

Adjacent sequences: A344770 A344771 A344772 * A344774 A344775 A344776

Keyword

nonn

Author

Antti Karttunen, May 31 2021

Status

approved