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A047813
Largest palindromic substring of n.
8
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 11, 2, 3, 4, 5, 6, 7, 8, 9, 2, 2, 22, 3, 4, 5, 6, 7, 8, 9, 3, 3, 3, 33, 4, 5, 6, 7, 8, 9, 4, 4, 4, 4, 44, 5, 6, 7, 8, 9, 5, 5, 5, 5, 5, 55, 6, 7, 8, 9, 6, 6, 6, 6, 6, 6, 66, 7, 8, 9, 7, 7, 7, 7, 7, 7, 7, 77, 8, 9, 8, 8, 8, 8, 8, 8, 8, 8, 88, 9, 9, 9, 9, 9, 9, 9
OFFSET
0,3
COMMENTS
a(n) = A262188(n,A262190(n)-1). - Reinhard Zumkeller, Sep 14 2015
EXAMPLE
a(1313) = Max{1,3,131,313} = 313.
MATHEMATICA
palQ[n_Integer, base_Integer] := Module[{idn = IntegerDigits[n, base]}, idn == Reverse[ idn]]; f[n_] := Block[{id = IntegerDigits@ n, mx = -Infinity}, k = Length@ id; While[k > 0 && mx == -Infinity, mx = Max[mx, Select[ FromDigits@# & /@ Partition[id, k, 1], palQ[#, 10] &]]; k--]; mx] (* Robert G. Wilson v, Aug 24 2011 *)
lps[n_]:=Module[{idn=IntegerDigits[n]}, Max[FromDigits/@Select[ Flatten[ Table[ Partition[ idn, i, 1], {i, Length[idn]}], 1], #==Reverse[#]&]]]; Array[ lps, 100, 0] (* Harvey P. Dale, Jan 09 2015 *)
PROG
(Haskell)
a047813 = last . a262188_row
-- Reinhard Zumkeller, Sep 14 2015, Aug 23 2011
(Python)
def c(s): return (s[0] != "0" or s == "0") and s == s[::-1]
def a(n):
s = str(n)
ss = (s[i:j] for i in range(len(s)) for j in range(i+1, len(s)+1))
return max(int(w) for w in ss if c(w))
print([a(n) for n in range(96)]) # Michael S. Branicky, Sep 18 2022
CROSSREFS
KEYWORD
nonn,easy,base,nice,look
STATUS
approved