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

1,3

Links

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

Indranil Ghosh, Braille Numerals

Example

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.

Prog

(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 str(j)+" "+str(i)
        j+=1
    i+=1

Crossrefs

Cf. A072283, A281015, A281017.

Sequence in context: A031359 A274790 A179852 * A110606 A346124 A241124

Adjacent sequences: A281017 A281018 A281019 * A281021 A281022 A281023

Keyword

nonn,base

Author

Indranil Ghosh, Jan 13 2017

Status

approved