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A307830
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Numbers k for which there exist no palindromic decagonal numbers (also known as 10-gonals) of length k.
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2
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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A307827 = {0, 1, 232, 27972, 76867, 25555552, 7154664517, 158229922851, 2028787878202, 2040061600402, 2733623263372, 52667666676625, 675972505279576, 28519896169891582, 73542836563824537, 74529570707592547, 25552469511596425552, 27835145788754153872, 62740719088091704726, 67047523077032574076, 77979812588521897977, 107838025535520838701};
a[n_] := Length[Select[A307827, IntegerLength[#] == n || (n == 1 && # == 0) &]];
Select[Range[20], a[#] == 0 &]
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CROSSREFS
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KEYWORD
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nonn,base,hard
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AUTHOR
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STATUS
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approved
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