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A224502 Prime numbers (together with one) whose representation in balanced ternary are palindromes. 3
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 * A361914 A047977 A139403
KEYWORD
nonn,base
AUTHOR
STATUS
approved

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Last modified March 19 06:25 EDT 2024. Contains 370953 sequences. (Running on oeis4.)