This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A029990 #19 Feb 10 2025 19:57:17 %S A029990 0,1,2,7,37,43,76,91,217,259,1064,1297,1333,1519,1555,2704,3367,7777, %T A029990 8029,9079,19747,46657,46873,47989,48205,54439,54655,54695,83979, %U A029990 118027,241304,279937,281449,287749,326599,707707,1679617 %N A029990 Numbers k such that k^2 is palindromic in base 6. %H A029990 Seiichi Manyama, <a href="/A029990/b029990.txt">Table of n, a(n) for n = 1..92</a> %H A029990 Patrick De Geest, <a href="https://www.worldofnumbers.com/nobase10pg2.htm">Palindromic Squares in bases 2 to 17</a> %t A029990 palindromicQ[n_, b_:10] := TrueQ[IntegerDigits[n, b] == Reverse[IntegerDigits[n, b]]]; Select[Range[1000], palindromicQ[#^2, 6] &] (* _Alonso del Arte_, Mar 05 2017 *) %o A029990 (PARI) ispal(n,base)=my(d=digits(n,base)); d==Vecrev(d) %o A029990 is(n)==ispal(n^2,6) \\ _Charles R Greathouse IV_, Mar 09 2017 %Y A029990 Cf. A007092. %Y A029990 Numbers k such that k^2 is palindromic in base b: A003166 (b=2), A029984 (b=3), A029986 (b=4), A029988 (b=5), this sequence (b=6), A029992 (b=7), A029805 (b=8), A029994 (b=9), A002778 (b=10), A029996 (b=11), A029737 (b=12), A029998 (b=13), A030072 (b=14), A030073 (b=15), A029733 (b=16), A118651 (b=17). %K A029990 nonn,base %O A029990 1,3 %A A029990 _Patrick De Geest_