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A133514 Biquadrateful (i.e. not biquadrate-free) palindromes. +0
1
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; listen)
OFFSET

1,1

COMMENT

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.

FORMULA

A002113 INTERSECTION A046101.

EXAMPLE

a(10) = 14641 = 11^4 (the smallest odd value in this sequence).

a(11) = 21312 = 2^6 * 3^2 * 37.

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

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

CROSSREFS

Cf. A002113, A046101.

Sequence in context: A005933 A112820 A062906 this_sequence A158587 A141546 A000517

Adjacent sequences: A133511 A133512 A133513 this_sequence A133515 A133516 A133517

KEYWORD

base,nonn

AUTHOR

Jonathan Vos Post (jvospost3(AT)gmail.com), Nov 30 2007

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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Last modified March 20 07:51 EDT 2010. Contains 173643 sequences.


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