A027717 -id:A027717 - cp's OEIS frontend

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

Patrick De Geest

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

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)

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

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 *)

More terms from Giovanni Resta, Aug 29 2018

A027716 Numbers k such that k^2 + k + 4 is a palindrome.

Original entry on oeis.org

0, 1, 20, 200, 219, 261, 2000, 2234, 2551, 2613, 20000, 20604, 200000, 202885, 205704, 218354, 2000000, 2155139, 2490266, 2620486, 20000000, 25882353, 200000000, 205705704, 2000000000, 2094600194, 20000000000, 20102030400, 20349812814, 21572321960

Offset: 1

Patrick De Geest

Includes 2*10^k for k>=2. - Robert Israel, Apr 16 2019

Giovanni Resta, Table of n, a(n) for n = 1..36
P. De Geest, Palindromic Quasi_Over_Squares of the form n^2+(n+X)

Cf. A027717, A027689, A027714, A027718.

palQ[n_] := Block[{d = IntegerDigits[n]}, d == Reverse[d]]; f[n_] := n^2 + n + 4; Select[Range[0, 10^5], palQ@ f@ # &] (* Giovanni Resta, Aug 29 2018 *)
Select[Range[0,3*10^6],PalindromeQ[#^2+#+4]&] (* The program generates the first 20 terms of the sequence. *) (* Harvey P. Dale, Jul 22 2024 *)

More terms from Giovanni Resta, Aug 29 2018

A027728 Palindromes of form k^2 + k + 5.

Original entry on oeis.org

5, 7, 11, 77, 161, 707, 5555, 16261, 50405, 53135, 7570757, 11988911, 16100161, 16544561, 162626261, 502858205, 758919857, 793464397, 11092829011, 11539593511, 5560873780655, 7424090904247, 7702753572077, 16515222251561, 57293477439275, 7246424554246427

Offset: 1

Patrick De Geest

Giovanni Resta, Table of n, a(n) for n = 1..46
P. De Geest, Palindromic Quasi_Over_Squares of the form n^2+(n+X)

Cf. A027718, A027690, A027754, A027755, A027717, A027728, A027721.

palQ[n_] := Block[{d = IntegerDigits[n]}, d == Reverse[d]]; f[n_] := n^2 + n + 5; Select[f@ Range[0, 10^5], palQ] (* Giovanni Resta, Aug 29 2018 *)
Select[Table[k^2+k+5,{k,0,852*10^5}],PalindromeQ] (* Harvey P. Dale, Aug 04 2025 *)

More terms from Giovanni Resta, Aug 28 2018

cp's OEIS Frontend

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

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A027716 Numbers k such that k^2 + k + 4 is a palindrome.

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A027728 Palindromes of form k^2 + k + 5.

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