A224502 Prime numbers (together with one) whose representation in balanced ternary are palindromes.

1, 7, 13, 43, 61, 73, 103, 367, 421, 457, 547, 601, 613, 757, 859, 1039, 1093, 3823, 4021, 4561, 4723, 4759, 5743, 6211, 6373, 6481, 6949, 7219, 7489, 7933, 8563, 8941, 9103, 9679, 29527, 30013, 31147, 31741, 33037, 35251, 36061, 36097, 36583, 37717, 39607, 41011, 42667, 43963, 44773, 45691, 47581, 49201

Offset

1,2

Comments

Intersection of A006005 and A134027.

Links

Malachi de Ælfweald and Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 (first 199 terms from Malachi de Ælfweald)

Wikipedia, Balanced ternary

Example

For n=5, a(5)=61 and in balanced ternary notation is 1ī1ī1.

Prog

(PARI)
bt(k, n)={
    sum(i=0, (n-1)\2,
        my(t=k%3-1);
        k\=3;
        n--;
        if(n==i, 3^n, 3^i+3^n)*t
    )
};
do(N)={
    my(v=List([1]), t);
    for(n=1, N,
        forstep(k=2, 3^((n+1)\2)-1, 3,
            t=bt(k, n);
            if(isprime(t), listput(v, t))
        )
    );
    vecsort(Vec(v))
}; \\ Charles R Greathouse IV, Apr 08 2013

Crossrefs

Sequence in context: A259184 A259186 A151781 * A361914 A047977 A139403

Adjacent sequences: A224499 A224500 A224501 * A224503 A224504 A224505

Keyword

nonn,base

Author

Malachi de Ælfweald, Apr 08 2013

Status

approved