A027727 - OEIS

%I #14 Aug 11 2024 14:41:29

%S 9,11,99,141,191,515,939,1001,19191,90309,92729,93339,109901,192291,

%T 939939,1303031,1997991,5605065,9003009,9887889,15066051,97111179,

%U 900030009,936696639,5193003915,11406560411,13028282031,15676667651,16473337461,90000300009

%N Palindromes of form k^2 + k + 9.

%C Palindromes h such that 4*h - 35 is a square. - _Bruno Berselli_, Aug 29 2018

%H Giovanni Resta, <a href="/A027727/b027727.txt">Table of n, a(n) for n = 1..71</a>

%H P. De Geest, <a href="https://www.worldofnumbers.com/quasimor.htm">Palindromic Quasi_Over_Squares of the form n^2+(n+X)</a>

%t 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 *)

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

%K nonn,base

%O 1,1

%A _Patrick De Geest_

%E More terms from _Giovanni Resta_, Aug 29 2018