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A230544 Solutions of the equation n'' = tau(n) * n', where n' and n'' are the first and the second arithmetic derivative of n. 0
1, 1255, 4063, 5359, 6583, 8615, 11623, 12047, 14359, 14863, 15943, 27644, 32471, 49271, 52607, 81599, 98471, 101687, 117647, 164327, 173447, 176471, 203327, 209207, 235271, 246647, 277271, 301607, 343271, 355871, 358367, 360623, 378047, 392471, 401927, 406607 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..36.

EXAMPLE

For n = 6583 we have tau(n) = 4, nā€™ =  256, nā€™ā€™= 1024 and 1024 = 4 * 256.

MAPLE

with(numtheory); P:= proc(q) local a1, a2, n, p;

for n from 1 to q do a1:=n*add(op(2, p)/op(1, p), p=ifactors(n)[2]); ;

a2:=a1*add(op(2, p)/op(1, p), p=ifactors(a1)[2]);

if a2=tau(n)*a1 then print(n); fi; od; end: P(10^6);

CROSSREFS

Cf. A000005, A003415, A068346.

Sequence in context: A023068 A062693 A067203 * A280928 A080718 A219993

Adjacent sequences:  A230541 A230542 A230543 * A230545 A230546 A230547

KEYWORD

nonn

AUTHOR

Paolo P. Lava, Oct 25 2013

STATUS

approved

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Last modified May 27 11:47 EDT 2022. Contains 354097 sequences. (Running on oeis4.)