A027727 Palindromes of form k^2 + k + 9.

9, 11, 99, 141, 191, 515, 939, 1001, 19191, 90309, 92729, 93339, 109901, 192291, 939939, 1303031, 1997991, 5605065, 9003009, 9887889, 15066051, 97111179, 900030009, 936696639, 5193003915, 11406560411, 13028282031, 15676667651, 16473337461, 90000300009

Offset: 1

Author

Patrick De Geest

Keywords

• nonn
• base

Comments

Palindromes h such that 4*h - 35 is a square. - Bruno Berselli, Aug 29 2018

Links

• Giovanni Resta, Table of n, a(n) for n = 1..71
• P. De Geest, Palindromic Quasi_Over_Squares of the form n^2+(n+X)

Crossrefs

Cf. A027726, A027694, A027757, A027758, A027725.

Programs

Mathematica

palQ[n_] := Block[{d = IntegerDigits[n]}, d == Reverse[d]]; f[n_] := n^2 + n + 9; Select[f@ Range[0, 10^5], palQ] (* Giovanni Resta, Aug 29 2018 *)
Select[Table[k^2+k+9,{k,0,300000}],PalindromeQ] (* Harvey P. Dale, Nov 21 2024 *)

Extensions

More terms from Giovanni Resta, Aug 29 2018