A027715 Palindromes of form k^2 + k + 3.

3, 5, 9, 33, 383, 555, 3663, 5115, 30803, 32223, 34043, 59295, 567765, 5912195, 37877873, 534141435, 957747759, 5356556535, 5646996465, 53205650235, 56511511565, 358023320853, 9571923291759, 30171944917103, 309961535169903, 356681959186653, 955371999173559

Offset: 1

Author

Patrick De Geest

Keywords

• nonn
• base

Comments

Palindromes h such that 4*h - 11 is a square. - Bruno Berselli, Aug 29 2018

Links

• Giovanni Resta, Table of n, a(n) for n = 1..50
• P. De Geest, Palindromic Quasi_Over_Squares of the form n^2+(n+X)

Crossrefs

Cf. A027714, A027688, A027752, A027753, A027713, A027717.

Programs

Mathematica

palQ[n_] := Block[{d = IntegerDigits[n]}, d == Reverse[d]]; f[n_] := n^2 + n + 3; Select[f@ Range[0, 10^5], palQ] (* Giovanni Resta, Aug 29 2018 *)

Extensions

More terms from Giovanni Resta, Aug 29 2018