1,1
19 is the smallest number that is centered k-gonal for exactly three k (k = 3, 6, or 18). Hence a(3) = 19
Sequence in context: A009895 A027371 A098576 this_sequence A155432 A155302 A155362
Adjacent sequences: A063770 A063771 A063772 this_sequence A063774 A063775 A063776
nonn
David W. Wilson (davidwwilson(AT)comcast.net), Aug 15 2001
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