A326145 Numbers n for which n - A007947(n) is equal to gcd(n - A007947(n), sigma(n) - A007947(n) - n).

6, 28, 496, 936, 1638, 8128, 33550336

Offset

1,1

Comments

Numbers n such that either A066503(n) and A326143(n) are both zero or A066503(n) is not zero and divides A326143(n).

Question: Are there any odd terms?

No other terms < 2^31.

Links

Table of n, a(n) for n=1..7.

Index entries for sequences where any odd perfect numbers must occur

Prog

(PARI)
A007947(n) = factorback(factorint(n)[, 1]);
isA326145(n) = { my(b=A007947(n), t=n-b, u = (sigma(n)-b)-n); (gcd(t, u)==t); };
\\ Or alternatively as:
isA326145(n) = { my(t=A326143(n), u=A066503(n)); ((!u && !t)||(u && !(t%u))); };

Crossrefs

Cf. A000203, A000396 (a subsequence), A007947, A066503, A228058, A326142, A326143, A326144.

Sequence in context: A325025 A325023 A138876 * A174633 A345004 A370789

Adjacent sequences: A326142 A326143 A326144 * A326146 A326147 A326148

Keyword

nonn,more

Author

Antti Karttunen, Jun 09 2019

Status

approved