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A276702 Numbers n>0 such that n’ = (n+1)’ + (n+2)’, where n’ is the arithmetic derivative of n. 0
28, 2056, 2865, 7157404, 10181420, 39593464, 92261602845 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(8) > 5*10^12. - Giovanni Resta, Sep 16 2016

LINKS

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

EXAMPLE

28’ = 32, 29’ = 1, 30’ = 31 and 32 = 1 + 31.

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 c=b+a then print(n-2); fi; od; end: P(10^9);

CROSSREFS

Cf. A003415.

Sequence in context: A294192 A202811 A285749 * A007219 A203751 A178187

Adjacent sequences:  A276699 A276700 A276701 * A276703 A276704 A276705

KEYWORD

nonn,more

AUTHOR

Paolo P. Lava, Sep 15 2016

EXTENSIONS

a(7) from Giovanni Resta, Sep 16 2016

STATUS

approved

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Last modified November 21 06:00 EST 2019. Contains 329350 sequences. (Running on oeis4.)