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A224502 Prime numbers (together with one) whose representation in balanced ternary are palindromes. 1
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 (list; graph; refs; listen; history; text; internal format)
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 * A047977 A139403 A087820

Adjacent sequences:  A224499 A224500 A224501 * A224503 A224504 A224505

KEYWORD

nonn,base

AUTHOR

Malachi de Ælfweald, Apr 08 2013

STATUS

approved

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Last modified August 21 01:18 EDT 2017. Contains 290855 sequences.