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A261914
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Largest palindrome < n (or 0 if n=0).
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3
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0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 9, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 33, 33, 33, 33, 33, 33, 33, 33, 33, 33, 33, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 55, 55, 55, 55, 55, 55, 55, 55, 55, 55, 55
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OFFSET
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0,4
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LINKS
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FORMULA
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MAPLE
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# Pal has list of palindromes; palfloor is A261423
palfloor:=proc(n) global Pal; local i;
for i from 1 to nops(Pal) do
if Pal[i]=n then return(n); fi;
if Pal[i]>n then return(Pal[i-1]); fi;
od:
end;
prevpal:=proc(n) global palfloor;
if n=0 then return(0);
elif member(n, Pal) then return(palfloor(n-1));
else return(palfloor(n)); fi; end;
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MATHEMATICA
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lp[n_]:=Module[{k=n-1}, While[!PalindromeQ[k], k--]; k]; Join[{0}, Array[lp, 70]] (* Harvey P. Dale, Oct 17 2022 *)
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PROG
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(Haskell)
a261914 n = a261914_list !! n
a261914_list = f 0 a002113_list where
f n ps@(p:ps'@(p':_)) = p : f (n + 1) (if n < p' then ps else ps')
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CROSSREFS
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Similar to but of course different from A261423.
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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