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A276701 Numbers n>0 such that n’ = (n-1)’ + (n-2)’, where n’ is the arithmetic derivative of n. 0
1, 3, 6, 20259, 43912, 563103, 18895035, 119847148, 305478634710 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(10) > 5*10^12. - Giovanni Resta, Sep 16 2016

LINKS

Table of n, a(n) for n=1..9.

EXAMPLE

6’ = 5, 5’ = 1, 4’ = 4 and 5 = 1 + 4.

MAPLE

with(numtheory): P:= proc(q) local a, b, c, n, p;

a:=n*add(op(2, p)/op(1, p), p=ifactors(n)[2]);

b:=(n-1)*add(op(2, p)/op(1, p), p=ifactors(n-1)[2]);

c:=(n-2)*add(op(2, p)/op(1, p), p=ifactors(n-2)[2]);

if a=b+c then print(n); fi; od; end: P(10^9);

CROSSREFS

Cf. A003415.

Sequence in context: A134901 A157564 A122182 * A157596 A111316 A297530

Adjacent sequences:  A276698 A276699 A276700 * A276702 A276703 A276704

KEYWORD

nonn,more

AUTHOR

Paolo P. Lava, Sep 15 2016

EXTENSIONS

a(9) from Giovanni Resta, Sep 16 2016

STATUS

approved

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Last modified November 20 02:34 EST 2019. Contains 329323 sequences. (Running on oeis4.)