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A287059 Least numbers k > 1 such that k'' = n*k', where k' and k'' are the first and the second arithmetic derivatives of k. 0
2, 4, 12, 160, 1255, 256, 12279, 3072, 1113823, 119120, 2191040, 4640768, 1835008, 12805120, 134217728 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..14.

EXAMPLE

a(3) = 160 because 160'' / 160' = 1296 / 432 = 3 and this is the least number to have this property.

MAPLE

with(numtheory): P:=proc(q) local a, b, k, n, p; for n from 0 to q do

for k from 2 to q do a:=k*add(op(2, p)/op(1, p), p=ifactors(k)[2]); b:=a*add(op(2, p)/op(1, p), p=ifactors(a)[2]); if b=n*a then print(k); break;

fi; od; od; end: P(10^9);

CROSSREFS

Cf. A003415, A068346.

Sequence in context: A053040 A154734 A291827 * A059085 A030064 A224886

Adjacent sequences:  A287056 A287057 A287058 * A287060 A287061 A287062

KEYWORD

nonn,more

AUTHOR

Paolo P. Lava, May 19 2017

STATUS

approved

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Last modified May 25 16:50 EDT 2022. Contains 354071 sequences. (Running on oeis4.)