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A216907
Smallest palindromic number of length 13 in two bases differing by n.
15
318713056300, 101252880671531, 778061547945037, 8047782883062742, 37866346844745025, 247644110790746909, 828823170233185174, 10556938000726441969, 10175119610486126649, 34575397981277771773, 91506808775956056797
OFFSET
1,1
COMMENTS
See comments sections of A216840 and A216841. Smallest of pair of bases are 8, 12, 14, 17, 19, 22, 24, 30, 32. For the remarkable case a(10), not only does the number have four 7s in a row in base 10, but it also has prime reversal there and in its 2nd base of 13-palindromicity, 42, no digit larger than 20 appears. A216*** cross-references are others in a collection of sequences that includes this one, while A171*** ones are various record multi-base palindromes.
EXAMPLE
The first term is 4506461646054 in base 8 and 1113578753111 in base 9.
KEYWORD
nonn,base
AUTHOR
James G. Merickel, Sep 19 2012
EXTENSIONS
a(10) added by James G. Merickel, Oct 17 2012
a(11) from Chai Wah Wu, Aug 20 2015
STATUS
approved