OFFSET
1,2
LINKS
P. De Geest, Palindromic nonagonals
FORMULA
9-gonal numbers are of the form (n(7n-5))/2.
MATHEMATICA
Select[Range[0, 10^5], PalindromeQ[PolygonalNumber[9, #]] &] (* Robert Price, Apr 29 2019 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
J. Lowell, Jul 10 2000
EXTENSIONS
Edited and extended by Patrick De Geest, Apr 13 2003.
STATUS
approved