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A028817 Palindromic squares with an odd number of digits. 2
1, 4, 9, 121, 484, 676, 10201, 12321, 14641, 40804, 44944, 69696, 94249, 1002001, 1234321, 4008004, 5221225, 6948496, 100020001, 102030201, 104060401, 121242121, 123454321, 125686521, 400080004, 404090404, 522808225, 617323716, 942060249, 10000200001 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..30.

Patrick De Geest, Subsets of Palindromic Squares

MATHEMATICA

id[n_] := IntegerDigits[n]; palQ[n_] := FromDigits[Reverse[id[n]]] == n; t = {}; Do[If[palQ[x = n^2] && OddQ[Length[id[x]]], AppendTo[t, x]], {n, 101000}]; t (* Jayanta Basu, May 13 2013 *)

Select[Range[100000]^2, PalindromeQ[#] && EvenQ[Floor[Log[10, #]]] &] (* Alonso del Arte, Oct 11 2019 *)

PROG

(Scala) def isPalindromic(n: BigInt): Boolean = n.toString == n.toString.reverse

val squares = ((1: BigInt) to (1000000: BigInt)).map(n => n * n)

squares.filter(n => isPalindromic(n) && n.toString.length % 2 == 1) // Alonso del Arte, Oct 07 2019

CROSSREFS

Cf. A002779, A028816.

Sequence in context: A158642 A131760 A002779 * A319483 A057136 A048411

Adjacent sequences:  A028814 A028815 A028816 * A028818 A028819 A028820

KEYWORD

nonn,base

AUTHOR

Patrick De Geest

STATUS

approved

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Last modified September 23 07:22 EDT 2020. Contains 337295 sequences. (Running on oeis4.)