A281020 Numbers with a prime number of raised dots in their Braille representation.

0, 1, 4, 6, 8, 12, 13, 15, 19, 21, 31, 47, 51, 67, 70, 74, 76, 78, 87, 91, 100, 104, 106, 108, 111, 127, 137, 140, 144, 146, 148, 157, 160, 164, 166, 168, 172, 173, 175, 177, 179, 180, 184, 186, 188, 197, 202, 203, 205, 207, 209, 217, 220, 224, 226, 228, 230, 234, 236, 238

Offset: 1

Author

Indranil Ghosh, Jan 13 2017

Keywords

• nonn
• base

Examples

			67 is in the sequence. 67, as evident from the link uploaded above, has 11 raised dots ("o") in its Braille representation and 11 is prime.
		

Links

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

Crossrefs

Cf. A072283, A281015, A281017.

Programs

Python

from sympy import isprime
B=[3, 1, 2, 2, 3, 2, 3, 4, 3, 2]
def a(n):
    s=0
    for i in str(n):
        s+=B[int(i)]
    return s+4
i=0
j=1
while j<=10000:
    if isprime(a(i))==True :
        print(f"{j} {i}")
        j+=1
    i+=1