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A229272 Numbers n for which n' + n and n' - n are both prime, n' being the arithmetic derivative of n. 4
210, 330, 390, 690, 798, 966, 1110, 1230, 2190, 2310, 2730, 3270, 4110, 4530, 4890, 5430, 6090, 6270, 6810, 6990, 7230, 7890, 8310, 8490, 9030, 9210, 9282, 10470, 10590, 10770, 12090, 12210, 12270, 12570, 12810, 12930, 13110, 13830, 14070, 17070, 17094, 17310 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Intersection of A165561 and A229270.

LINKS

Paolo P. Lava, Table of n, a(n) for n = 1..300

MAPLE

with(numtheory); P:=proc(q) local a, n, p; for n from 1 to q do

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

if isprime(a+n) and isprime(a-n) then print(n); fi;

od; end: P(10^5);

PROG

(Python)

from sympy import isprime, factorint

A229272 = []

for n in range(1, 10**5):

....np = sum([int(n*e/p) for p, e in factorint(n).items()]) if n > 1 else 0

....if isprime(np+n) and isprime(np-n):

........A229272.append(n)

# Chai Wah Wu, Aug 21 2014

CROSSREFS

Cf. A003415, A165561, A165562, A229269-A229271.

Sequence in context: A074159 A033993 A046386 * A046402 A258359 A264664

Adjacent sequences:  A229269 A229270 A229271 * A229273 A229274 A229275

KEYWORD

nonn

AUTHOR

Paolo P. Lava, Sep 18 2013

STATUS

approved

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Last modified August 20 11:27 EDT 2017. Contains 290835 sequences.