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

1,2

Links

Table of n, a(n) for n=1..23.

P. De Geest, Palindromic nonagonals

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 *)

Crossrefs

Cf. A001106, A055560.

Sequence in context: A053904 A058607 A298835 * A352384 A143167 A201532

Adjacent sequences: A082720 A082721 A082722 * A082724 A082725 A082726

Keyword

nonn,base

Author

Patrick De Geest, Apr 13 2003

Status

approved