A028348 - OEIS

A028348

Numbers k such that k^2 + 3*k + 1 is a palindrome.

1, 2, 6, 10, 12, 21, 29, 35, 94, 100, 117, 122, 325, 380, 442, 1000, 1132, 1307, 3073, 10000, 10325, 10602, 12652, 13207, 30404, 30834, 31474, 32672, 95603, 96439, 100000, 110665, 234566, 236026, 308863, 709781, 987443, 1000000, 1060602, 1099265, 1172835

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..41.

Patrick De Geest, Palindromic Quasi_Under_Squares of the form n+(n+1)^2

MATHEMATICA

palQ[n_]:=Module[{id=IntegerDigits[n^2+3n+1]}, id==Reverse[id]]; Select[Range[240000], palQ] (* Harvey P. Dale, Apr 17 2012 *)

Select[Range[1173000], PalindromeQ[#^2+3#+1]&] (* Harvey P. Dale, Jun 09 2022 *)

CROSSREFS

Cf. A028349.

Sequence in context: A190789 A373049 A071638 * A214963 A140776 A277238