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A028348 Numbers k such that k^2 + 3*k + 1 is a palindrome. 1

%I

%S 1,2,6,10,12,21,29,35,94,100,117,122,325,380,442,1000,1132,1307,3073,

%T 10000,10325,10602,12652,13207,30404,30834,31474,32672,95603,96439,

%U 100000,110665,234566,236026,308863,709781,987443,1000000,1060602,1099265,1172835

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

%H Patrick De Geest, <a href="http://www.worldofnumbers.com/sumpower.htm">Palindromic Quasi_Under_Squares of the form n+(n+1)^2</a>

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

%Y Cf. A028349.

%K nonn,base

%O 1,2

%A _Patrick De Geest_

%E Extended and definition corrected by _T. D. Noe_, Apr 17 2012

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Last modified May 24 16:36 EDT 2022. Contains 354042 sequences. (Running on oeis4.)