1,1

Previous name was: There exist no palindromic nonagonals (enneagonals) of length n.

P. De Geest, Palindromic nonagonals

A082723 = {0, 1, 9, 111, 474, 969, 6666, 18981, 67276, 4411144, 6964696, 15444451, 57966975, 448707844, 460595064, 579696975, 931929139, 994040499, 1227667221, 9698998969, 61556965516, 664248842466, 699030030996, 99451743334715499, 428987160061789824, 950178723327871059, 1757445628265447571, 4404972454542794044, 9433971680861793349, 499583536595635385994, 1637992008558002997361, 19874891310701319847891};

A082722[n_] := Length[Select[A082723, IntegerLength[#] == n || (n == 1 && # == 0) &]];

Select[Range[22], A082722[#] == 0 &] (* Robert Price, Apr 29 2019 *)

Cf. A034822, A059868, A082721, A059869, A059870, A034307.

Sequence in context: A116534 A130533 A231384 * A329222 A030416 A353588

Adjacent sequences: A082719 A082720 A082721 * A082723 A082724 A082725

nonn,base,hard

Patrick De Geest, Apr 13 2003

Definition edited by Jon E. Schoenfield, Sep 15 2013

approved