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A027720
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Palindromes of form k^2 + 1.
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5
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1, 2, 5, 101, 626, 10001, 1000001, 1040401, 2217122, 5053505, 100000001, 101808101, 10000000001, 10182828101, 10408080401, 28053235082, 1000000000001, 1000400040001, 1018262628101, 7534662664357, 100000000000001, 100018000810001, 101826464628101
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refs;
listen;
history;
text;
internal format)
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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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MATHEMATICA
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palQ[n_] := Block[{d = IntegerDigits[n]}, d == Reverse[d]]; Select[Range[0, 10^5]^2 + 1, palQ] (* Giovanni Resta, Aug 29 2018 *)
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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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