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%I #18 May 03 2021 15:37:11
%S 2,3,7,8,12,14,16,18,21,23,25,27,29,30,32,34,36,38,41,43,47,49,50,52,
%T 58,61,63,67,69,70,72,74,76,78,81,83,85,87,89,92,94,96,98,101,109,110,
%U 190,200,355,445,454,456,465,535,544,546,553,557,564,566,575,645
%N Numbers with a prime number of dots and a prime number of dashes in their International Morse numeral representation.
%C This uses the current ITU standard Morse code.
%C This sequence is the intersection of A281015 and A281017.
%H Indranil Ghosh, <a href="/A281018/b281018.txt">Table of n, a(n) for n = 1..10000</a>
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Morse_code">Morse Code</a>
%e 27 is in the sequence because it is both in A281015 and A281017.
%o (Python) # uses[A280913, A280916]
%o from sympy import isprime
%o i=0
%o j=1
%o while j<=1000:
%o if isprime(A280913(i)) and isprime(A280916(i)):
%o print(str(j)+" "+str(i))
%o j+=1
%o i+=1
%o (PARI) select( {is_A281018(n)=is_A281017(n)&&is_A281015(n)}, [0..666]) \\ _M. F. Hasler_, Jun 22 2020
%Y Cf. A280913, A280916, A281015, A281017.
%Y Cf. A060109 (Morse code for n).
%K nonn,base
%O 1,1
%A _Indranil Ghosh_, Jan 13 2017
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