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A082723 Palindromic nonagonal (or 9-gonal or enneagonal) numbers. 6
1, 9, 111, 474, 969, 6666, 18981, 67276, 4411144, 6964696, 15444451, 57966975, 448707844, 460595064, 579696975, 931929139, 994040499, 1227667221, 9698998969, 61556965516, 664248842466, 699030030996, 99451743334715499 (list; graph; refs; listen; history; text; internal format)
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 * A143167 A201532 A180788

Adjacent sequences:  A082720 A082721 A082722 * A082724 A082725 A082726

KEYWORD

nonn,base

AUTHOR

Patrick De Geest, Apr 13 2003

STATUS

approved

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Last modified May 28 14:47 EDT 2020. Contains 334684 sequences. (Running on oeis4.)