A326145 - OEIS

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

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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

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

KEYWORD

nonn,more

AUTHOR

STATUS

approved