This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 A325991 Adjacent sequences:  A229269 A229270 A229271 * A229273 A229274 A229275 KEYWORD nonn AUTHOR Paolo P. Lava, Sep 18 2013 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 5 13:26 EST 2019. Contains 329751 sequences. (Running on oeis4.)