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%I #21 Jun 09 2022 16:26:05
%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 *)
%t Select[Range[1173000],PalindromeQ[#^2+3#+1]&] (* _Harvey P. Dale_, Jun 09 2022 *)
%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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