A281015 Numbers with a prime number of dots in their International Morse numeral representation.

2, 3, 5, 7, 8, 11, 12, 14, 16, 18, 19, 20, 21, 23, 25, 27, 29, 30, 32, 34, 36, 38, 41, 43, 47, 49, 50, 52, 58, 61, 63, 67, 69, 70, 72, 74, 76, 78, 80, 81, 83, 85, 87, 89, 91, 92, 94, 96, 98, 99, 101, 102, 104, 106, 108, 109, 110, 111, 113, 115, 117, 119, 120, 122, 124, 126

Offset: 1

Author

Indranil Ghosh, Jan 13 2017

Keywords

• nonn
• base

Comments

The Morse code is written in current ITU standard.

Indices of primes in A280913. - M. F. Hasler, Jun 22 2020

Examples

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

Links

• Indranil Ghosh, Table of n, a(n) for n = 1..10000
• Wikipedia, Morse Code

Crossrefs

Cf. A060109 (Morse code for n), A280913 (number of dots in Morse code for n).

Cf. A281017 (same for dashes), A281018 (intersection of the two).

Cf. A280998, A280999.

Programs

PARI

select( {is_A281015(n)=isprime(A280913(n))}, [0..150]) \\ M. F. Hasler, Jun 22 2020

Python

# uses[A280913]
from sympy import isprime
i=0
j=1
while j<=100:
    if isprime(A280913(i)):
        print(str(j)+" "+str(i))
        j+=1
    i+=1