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A281017 Numbers with a prime number of dashes in their International Morse numeral representation. 5
0, 2, 3, 7, 8, 12, 14, 16, 18, 21, 23, 25, 27, 29, 30, 32, 34, 35, 36, 38, 41, 43, 44, 46, 47, 49, 50, 52, 53, 57, 58, 61, 63, 64, 66, 67, 69, 70, 72, 74, 75, 76, 78, 81, 83, 85, 87, 89, 92, 94, 96, 98, 101, 103, 107, 109, 110, 112, 118, 121, 125, 129, 130, 134, 136, 143 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The Morse code is written in current ITU standard.

Indices of primes in A280916. - M. F. Hasler, Jun 22 2020

LINKS

Indranil Ghosh, Table of n, a(n) for n = 1..10000

Wikipedia, Morse Code

FORMULA

This A281017 = { n | A280916(n) is prime }. - M. F. Hasler, Jun 22 2020

EXAMPLE

27 is in the sequence because 27 in its Morse numeral representation is written as '..--- --...' which has 5 dashes and 5 is prime.

PROG

(Python) # uses[A280916]

from sympy import isprime

i=0

j=1

while j<=100:

    if isprime(A280916(i)):

        print(str(j)+" "+str(i))

        j+=1

    i+=1

(PARI) select( {is_A281017(n)=isprime(A280916(n))}, [0..150]) \\ M. F. Hasler, Jun 22 2020

CROSSREFS

Cf. A060109 (Morse code for n), A280916 (number of dashes in Morse code for n).

Cf. A281015 (same for dots), A281018 (intersection of the two).

Cf. A280998, A280999.

Sequence in context: A331078 A032967 A111101 * A281018 A184860 A242655

Adjacent sequences:  A281014 A281015 A281016 * A281018 A281019 A281020

KEYWORD

nonn,base

AUTHOR

Indranil Ghosh, Jan 13 2017

STATUS

approved

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Last modified August 4 18:15 EDT 2021. Contains 346455 sequences. (Running on oeis4.)