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A047739
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Economical palindromes.
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0
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343, 1331, 10201, 14641, 31213, 94249, 1030301, 1332331, 1367631, 1478741, 2060602, 2513152, 2551552, 2570752, 2939392, 2977792, 3090903, 3498943, 3637363, 3735373, 3850583, 5221225, 5265625, 5734375, 6948496, 11288211, 11333311, 12100121, 12499421, 13577531, 14655641, 22666622, 27700772, 29399392, 31244213, 33999933, 38988983, 58344385, 71111117, 100020001, 100585001, 101000101, 104060401, 104555401, 106878601
(list;
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refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..45.
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EXAMPLE
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343 = 7^3; 3 digits in 343, 2 digits in 7^3, so 343 is economical.
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MATHEMATICA
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d[n_]:=IntegerDigits[n]; palQ[n_]:=Reverse[(x=d[n])]==x; ecQ[n_]:=Length[Flatten[d[{First/@(x=FactorInteger[n]), DeleteCases[Last/@x, 1]}]]] < Length[d[n]]; t={}; Do[If[palQ[n] && ecQ[n], AppendTo[t, n]], {n, 3860000}]; t (* Jayanta Basu, May 16 2013 *)
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CROSSREFS
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Cf. A002113, A046759.
Sequence in context: A117689 A178374 A179147 * A052084 A075546 A167733
Adjacent sequences: A047736 A047737 A047738 * A047740 A047741 A047742
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KEYWORD
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nonn,base
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AUTHOR
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Carlos Rivera
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EXTENSIONS
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a(11)-a(45) from Donovan Johnson, Nov 24 2010
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STATUS
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approved
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