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A083250 Numbers n for which abs(A045763(n) - A073757(n)) = 3, i.e., signed difference of size of related and unrelated sets to n equals either 3 or -3. 4
3, 825, 1755, 4641, 5313, 56865, 58395, 140049, 159152763, 361701435 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

No more terms below 10^9. - Amiram Eldar, Jan 27 2019

LINKS

Table of n, a(n) for n=1..10.

EXAMPLE

For n=140049: d=40 divisors, r=70026 coprimes and u=70023 unrelated numbers to n; abs(r-u) = 3.

MATHEMATICA

Do[r=EulerPhi[n]; d=DivisorSigma[0, n]; u=n-r-d+1; df=2*u-n; If[Equal[Abs[df], 3], Print[n(*, {d, r, u}*)]], {n, 1, 100}]

PROG

(PARI) isok(n) = abs(n-2*eulerphi(n)-2*numdiv(n)+2) == 3; \\ Michel Marcus, Jul 30 2017

CROSSREFS

Cf. A000005, A000010, A045763, A073757, A083243-A083249.

Sequence in context: A293252 A341567 A287695 * A096086 A062658 A266654

Adjacent sequences:  A083247 A083248 A083249 * A083251 A083252 A083253

KEYWORD

nonn,more

AUTHOR

Labos Elemer, May 07 2003

EXTENSIONS

a(9)-a(10) from Amiram Eldar, Jan 27 2019

STATUS

approved

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Last modified August 16 07:50 EDT 2022. Contains 356160 sequences. (Running on oeis4.)