A027721 Palindromes of form k^2 + k + 6.

6, 8, 606, 656, 818, 83238, 6177716, 6505056, 8343438, 8681868, 834545438, 21543634512, 69872727896, 83456565438, 85425552458, 8032131312308, 8255470745528, 8345676765438, 8716172716178, 8766434346678, 8915858585198, 8973808083798, 213296020692312

Offset: 1

Author

Patrick De Geest

Keywords

• nonn
• base

Comments

Palindromes h such that 4*h - 23 is a square. - Bruno Berselli, Aug 29 2018

Links

• Giovanni Resta, Table of n, a(n) for n = 1..34
• P. De Geest, Palindromic Quasi_Over_Squares of the form n^2+(n+X)

Crossrefs

Cf. A027729, A027691, A027728, A027723.

Programs

Mathematica

palQ[n_] := Block[{d = IntegerDigits[n]}, d == Reverse[d]]; f[n_] := n^2 + n + 6; Select[f@ Range[0, 10^5], palQ] (* Giovanni Resta, Aug 29 2018 *)

Formula

a(n) = A027729(n)^2 + A027729(n) + 6. - Giovanni Resta, Aug 27 2018

Extensions

More terms from Giovanni Resta, Aug 27 2018