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A028504
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Palindromes of form k*(k+2); or palindromes 1 less than a square.
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5
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0, 3, 8, 99, 323, 575, 4224, 5775, 9999, 36863, 42024, 999999, 3055503, 3640463, 5597955, 8803088, 32855823, 99999999, 360696063, 422919224, 9999999999, 30485858403, 30536863503, 32154945123, 59080108095, 86310801368, 304816618403, 999999999999, 3490500050943
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OFFSET
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1,2
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COMMENTS
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10^(2*m) - 1 for m > 0 are terms. - Chai Wah Wu, May 25 2017
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LINKS
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FORMULA
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EXAMPLE
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4224 belongs to this sequence as 4225 = 65^2.
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MATHEMATICA
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palQ[n_] := Block[{d = IntegerDigits[n]}, d == Reverse[d]]; Select[Range[10000]^2 - 1, palQ] (* Giovanni Resta, Aug 29 2018 *)
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PROG
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(ARIBAS): stop := 400000; m := 1; while m < stop do s := m*m - 1; if s = int_reverse(s) then write(s, " "); end; inc(m); end;
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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