A029987 Squares which are palindromes in base 4.

0, 1, 25, 289, 441, 4225, 5041, 6889, 66049, 74529, 78961, 100489, 1050625, 1113025, 16785409, 17313921, 17581249, 19368801, 26594649, 26822041, 27258841, 268468225, 272613121, 284428225, 297183121, 4295098369

Offset: 1

Author

Patrick De Geest

Keywords

• nonn
• base

Examples

			5^2 = 25 in base 4 is 121, which is a palindrome, hence 25 is in the sequence.
6^2 = 36 in base 4 is 210, which is not a palindrome, so 36 is not in the sequence.
		

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..408
• Patrick De Geest, Palindromic Squares in bases 2 to 17

Crossrefs

Cf. A029986.

Programs

Mathematica

palindromicQ[n_, b_:10] := TrueQ[IntegerDigits[n, b] == Reverse[IntegerDigits[n, b]]]; Select[Range[1000]^2, palindromicQ[#, 4] &] (* Alonso del Arte, Mar 04 2017 *)
Select[Range[0,70000]^2,IntegerDigits[#,4]==Reverse[IntegerDigits[#,4]]&] (* Harvey P. Dale, May 07 2022 *)

PARI

lista(nn) = for (n=0, nn, d = digits(n^2, 4); if (Vecrev(d) == d, print1(n^2, ", "))); \\ Michel Marcus, Mar 05 2017