A082723 Palindromic nonagonal (or 9-gonal or enneagonal) numbers.

1, 9, 111, 474, 969, 6666, 18981, 67276, 4411144, 6964696, 15444451, 57966975, 448707844, 460595064, 579696975, 931929139, 994040499, 1227667221, 9698998969, 61556965516, 664248842466, 699030030996, 99451743334715499

Offset: 1

Author

Patrick De Geest, Apr 13 2003

Keywords

• nonn
• base

Links

• P. De Geest, Palindromic nonagonals

Crossrefs

Cf. A001106, A055560.

Programs

Mathematica

palQ[n_]:=Module[{idn=IntegerDigits[n]},idn==Reverse[idn]]; Select[Table[ (n(7n-5))/2,{n,170000000}],palQ] (* Harvey P. Dale, Nov 15 2011 *)