OFFSET
1
COMMENTS
LINKS
FORMULA
a(n) = [A336562(n) == 0].
For all n >= 1, a(n) <= A336556(n).
a(n) = 1 => A336355(n) = 0.
From Antti Karttunen, May 09 2022: (Start)
In all three formulas, [ ] stands for the Iverson brackets, yielding 1 only when the two sequences obtain an equal value at n, and 0 otherwise:
(End)
PROG
(PARI)
is_fun_mult_on_n(fun, n) = { my(f=factor(n)); prod(k=1, #f~, fun(f[k, 1]^f[k, 2]))==fun(n); };
A051027(n) = sigma(sigma(n));
(PARI) A336546(n) = { my(f=factor(n)); (sigma(n)==lcm(vector(#f~, k, sigma(f[k, 1]^f[k, 2])))); }; \\ Antti Karttunen, May 09 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 25 2020
EXTENSIONS
The old definition moved to comments and replaced with a more generic, but equivalent definition by Antti Karttunen, May 09 2022
STATUS
approved