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A133514
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Biquadrateful (i.e. not biquadrate-free) palindromes.
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0
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272, 464, 656, 848, 2112, 2992, 4224, 6336, 8448, 14641, 21312, 21712, 23232, 23632, 25152, 25552, 25952, 27072, 27472, 27872, 29392, 29792, 31213, 40304, 40704, 42224, 42624, 44144, 44544, 44944, 46064, 46464, 46864, 48384, 48784, 61216
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| This is to A035133 as 4th powers are to cubes. To make an analogy between analogies, the preceding sentence is to "A130873 is to 4th powers as A120398 is to cubes" as palindromes are to sums of two distinct prime powers.
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FORMULA
| A002113 INTERSECTION A046101.
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EXAMPLE
| a(10) = 14641 = 11^4 (the smallest odd value in this sequence).
a(11) = 21312 = 2^6 * 3^2 * 37.
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MAPLE
| isA046101 := proc(n) local ifs, f ; ifs := ifactors(n)[2] ; for f in ifs do if op(2, f) >= 4 then RETURN(true) ; fi ; od: RETURN(false) ; end: isA002113 := proc(n) local digs, i ; digs := convert(n, base, 10) ; for i from 1 to nops(digs) do if op(i, digs) <> op(-i, digs) then RETURN(false) ; fi ; od: RETURN(true) ; end: isA133514 := proc(n) isA046101(n) and isA002113(n) ; end: for n from 1 to 100000 do if isA133514(n) then printf("%d, ", n) ; fi ; od: - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 12 2008
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MATHEMATICA
| a = {}; For[n = 2, n < 100000, n++, If[FromDigits[Reverse[IntegerDigits[n]]] == n, b = 0; For[l = 1, l < Length[FactorInteger[n]] + 1, l++, If[FactorInteger[n][[l, 2]] > 3, b = 1]]; If[b == 1, AppendTo[a, n]]]]; a - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Dec 26 2007
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CROSSREFS
| Cf. A002113, A046101.
Sequence in context: A005933 A112820 A062906 * A158587 A178268 A205345
Adjacent sequences: A133511 A133512 A133513 * A133515 A133516 A133517
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KEYWORD
| base,nonn
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AUTHOR
| Jonathan Vos Post (jvospost3(AT)gmail.com), Nov 30 2007
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EXTENSIONS
| More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Dec 26 2007
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 12 2008
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