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%I #8 May 17 2019 05:55:50
%S 1,9,111,474,969,6666,18981,67276,4411144,6964696,15444451,57966975,
%T 448707844,460595064,579696975,931929139,994040499,1227667221,
%U 9698998969,61556965516,664248842466,699030030996,99451743334715499
%N Palindromic nonagonal (or 9-gonal or enneagonal) numbers.
%H P. De Geest, <a href="http://www.worldofnumbers.com/nona.htm">Palindromic nonagonals</a>
%t palQ[n_]:=Module[{idn=IntegerDigits[n]},idn==Reverse[idn]]; Select[Table[ (n(7n-5))/2,{n,170000000}],palQ] (* _Harvey P. Dale_, Nov 15 2011 *)
%Y Cf. A001106, A055560.
%K nonn,base
%O 1,2
%A _Patrick De Geest_, Apr 13 2003
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