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A028336
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Positive numbers k such that k*(k+1) is a palindrome.
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4
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1, 2, 16, 77, 538, 1621, 2457, 5291, 5313, 52008, 142401, 143498, 1610151, 1713543, 4670028, 5218983, 15137566, 15282411, 15814148, 47370058, 50702751, 142594226, 166691108, 1694576061, 2554554552, 25541432472, 47878213558, 77714915542, 155482156418
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OFFSET
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1,2
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COMMENTS
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For additional terms, see the De Geest link.
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LINKS
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MATHEMATICA
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Select[Range[500000], PalindromeQ[#(#+1)] &] (* or *) Select[Range[50000], IntegerDigits[#(#+1)] == Reverse[ IntegerDigits[#(#+1)]] &] (* G. C. Greubel, Nov 24 2016 *)
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PROG
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(PARI) isok(k) = my(d = digits(k*(k+1))); Vecrev(d) == d; \\ Michel Marcus, Nov 09 2017
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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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