A255161 Prime numbers with more than one 1 < k < 10 for which the base-k representation is palindromic.

2, 3, 5, 7, 17, 31, 67, 73, 107, 109, 127, 173, 191, 227, 257, 373, 701, 1667, 2293, 4289, 5189, 6761, 7517, 7703, 9103, 12547, 14891, 15083, 16319, 19433, 28807, 31727, 47653, 65537, 69313, 83269, 85093, 86293, 262657, 295433, 444713, 663571, 1053953, 1063613

Offset

1,1

Links

Chai Wah Wu, Table of n, a(n) for n = 1..3793 (all terms < 10^14).

Example

17 belongs to the sequence as for more than one one-digit base (2 and 4) its base representation is palindromic (in base 2 the representation is 10001, in base 4 the representation is 101).
13 does not belong to the sequence since only in one one-digit base (namely, base 3) is its base representation (111) palindromic.

Prog

(PARI) ispal(n, b)=my(v=digits(n, b)); for(i=1, #v\2, if(v[i]!=v[#v+1-i], return(0))); 1
is(n)=sum(b=2, 9, ispal(n, b))>1 && isprime(n) \\ Charles R Greathouse IV, Feb 21 2015

Crossrefs

Cf. A087155 (without restriction k<10).

Sequence in context: A074788 A262833 A070805 * A103385 A103389 A103387

Adjacent sequences: A255158 A255159 A255160 * A255162 A255163 A255164

Keyword

nonn,base

Author

Pierandrea Formusa, Feb 15 2015

Status

approved