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A068616
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Starting from a(1)=7, each subsequent term is the minimal square obtained by inserting at least one digit into the previous term.
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1
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7, 576, 5476, 54756, 1547536, 154753600, 15475360000, 1547536000000, 154753600000000, 15475360000000000, 1547536000000000000, 154753600000000000000, 15475360000000000000000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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FORMULA
| For n>=5, a(n) = 1547536*100^(n-5).
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EXAMPLE
| a(2)=576 hence a(3) = 5476 the smallest square formed from 576.
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MAPLE
| Digits := 30 : isContain := proc(n, k) local ndigs, kdigs, f, d ; ndigs := convert(n, base, 10) ; kdigs := convert(k, base, 10) ; f := 1 : for d from 1 to nops(ndigs) do if f > nops(kdigs) then RETURN(false) ; fi ; while op(f, kdigs) <> op(d, ndigs) do f := f+1 ; if f > nops(kdigs) then RETURN(false) ; fi ; od: f := f+1 ; od: RETURN(true) ; end: n := 7 ; s := 8 : while true do while not isContain(n, s^2) do s := s+1 : od ; print(s^2) ; n := s^2: s := ceil(sqrt(s^2+1)) : od: - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 26 2007
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CROSSREFS
| Cf. A068175, A068176, A068177, A068178.
Sequence in context: A126196 A093169 A159029 * A080810 A153405 A203680
Adjacent sequences: A068613 A068614 A068615 * A068617 A068618 A068619
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KEYWORD
| base,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Feb 25 2002
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EXTENSIONS
| More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 26 2007
5 more terms from Sean A. Irvine (sairvin(AT)xtra.co.nz), Sep 27 2009
Edited by Max Alekseyev (maxale(AT)gmail.com), Oct 12 2009
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